Search Results

Search found 40165 results on 1607 pages for 'function pointers'.

Page 44/1607 | < Previous Page | 40 41 42 43 44 45 46 47 48 49 50 51  | Next Page >

• Function Folding in #PowerQuery

  - by Darren Gosbell

  Originally posted on: http://geekswithblogs.net/darrengosbell/archive/2014/05/16/function-folding-in-powerquery.aspxLooking at a typical Power Query query you will noticed that it's made up of a number of small steps. As an example take a look at the query I did in my previous post about joining a fact table to a slowly changing dimension. It was roughly built up of the following steps: Get all records from the fact table Get all records from the dimension table do an outer join between these two tables on the business key (resulting in an increase in the row count as there are multiple records in the dimension table for each business key) Filter out the excess rows introduced in step 3 remove extra columns that are not required in the final result set. If Power Query was to execute a query like this literally, following the same steps in the same order it would not be overly efficient. Particularly if your two source tables were quite large. However Power Query has a feature called function folding where it can take a number of these small steps and push them down to the data source. The degree of function folding that can be performed depends on the data source, As you might expect, relational data sources like SQL Server, Oracle and Teradata support folding, but so do some of the other sources like OData, Exchange and Active Directory. To explore how this works I took the data from my previous post and loaded it into a SQL database. Then I converted my Power Query expression to source it's data from that database. Below is the resulting Power Query which I edited by hand so that the whole thing can be shown in a single expression: let     SqlSource = Sql.Database("localhost", "PowerQueryTest"),     BU = SqlSource{[Schema="dbo",Item="BU"]}[Data],     Fact = SqlSource{[Schema="dbo",Item="fact"]}[Data],     Source = Table.NestedJoin(Fact,{"BU_Code"},BU,{"BU_Code"},"NewColumn"),     LeftJoin = Table.ExpandTableColumn(Source, "NewColumn"                                   , {"BU_Key", "StartDate", "EndDate"}                                   , {"BU_Key", "StartDate", "EndDate"}),     BetweenFilter = Table.SelectRows(LeftJoin, each (([Date] >= [StartDate]) and ([Date] <= [EndDate])) ),     RemovedColumns = Table.RemoveColumns(BetweenFilter,{"StartDate", "EndDate"}) in     RemovedColumns If the above query was run step by step in a literal fashion you would expect it to run two queries against the SQL database doing "SELECT * …" from both tables. However a profiler trace shows just the following single SQL query: select [_].[BU_Code],     [_].[Date],     [_].[Amount],     [_].[BU_Key] from (     select [$Outer].[BU_Code],         [$Outer].[Date],         [$Outer].[Amount],         [$Inner].[BU_Key],         [$Inner].[StartDate],         [$Inner].[EndDate]     from [dbo].[fact] as [$Outer]     left outer join     (         select [_].[BU_Key] as [BU_Key],             [_].[BU_Code] as [BU_Code2],             [_].[BU_Name] as [BU_Name],             [_].[StartDate] as [StartDate],             [_].[EndDate] as [EndDate]         from [dbo].[BU] as [_]     ) as [$Inner] on ([$Outer].[BU_Code] = [$Inner].[BU_Code2] or [$Outer].[BU_Code] is null and [$Inner].[BU_Code2] is null) ) as [_] where [_].[Date] >= [_].[StartDate] and [_].[Date] <= [_].[EndDate] The resulting query is a little strange, you can probably tell that it was generated programmatically. But if you look closely you'll notice that every single part of the Power Query formula has been pushed down to SQL Server. Power Query itself ends up just constructing the query and passing the results back to Excel, it does not do any of the data transformation steps itself. So now you can feel a bit more comfortable showing Power Query to your less technical Colleagues knowing that the tool will do it's best fold all the  small steps in Power Query down the most efficient query that it can against the source systems.

  Read the article

• ASP.NET Workaround: Calling a JavaScript Function from a HyperLinkField in a GridView

  You can call a JavaScript function when a user clicks a HyperLinkField in a GridView control—you just need to use this workaround.

  Read the article

• Unable to Call Instantiate in Class Member Function

  - by onguarde

  The following javascript is attached to a gameObject. var instance : GameObject; class eg_class { function eg_func(){ var thePrefab : GameObject; instance = Instantiate(thePrefab); } } Error, Unknown identifier: 'instance'. Unknown identifier: 'Instantiate'. Questions, 1) Why is it that "instance" cannot be accessed within a class? Isn't it supposed to be a public variable? 2) "Instantiate" function works in Start()/Update() root functions. Is there a way to make it work from within member functions? Thanks in advance!

  Read the article

• Function that requires many parameters

  - by user877329

  I have a problem related to this: Are there guidelines on how many parameters a function should accept? In my case, I have a function that describes a rounded rectangle. The caller specifies An integer which determines how the rectangle should be merged into previously created shapes An Anchor, which is a point that is used for alignment (right, left, top, bottom etc). (0,-1) means that position (next parameter) describes the top, middle point of the rectangle. The position of the rectangle Width and height Corner radius Should I use Parameter Object pattern in this case? It is hard to see how these parameters are related

  Read the article

• python factory function best practices

  - by Jason S

  Suppose I have a file foo.py containing a class Foo: class Foo(object): def __init__(self, data): ... Now I want to add a function that creates a Foo object in a certain way from raw source data. Should I put it as a static method in Foo or as another separate function? class Foo(object): def __init__(self, data): ... # option 1: @staticmethod def fromSourceData(sourceData): return Foo(processData(sourceData)) # option 2: def makeFoo(sourceData): return Foo(processData(sourceData)) I don't know whether it's more important to be convenient for users: foo1 = foo.makeFoo(sourceData) or whether it's more important to maintain clear coupling between the method and the class: foo1 = foo.Foo.fromSourceData(sourceData)

  Read the article

• Calling a parameterized javascript function from php [migrated]

  - by Ginger

  I need to call a javascript function from php, by passing a value in php variable. My code goes like this: echo '<tr class="trlight"><td onclick="callVehicle('.$qry_vehicleid.');"><label>Call Vehicle</label>&nbsp;</td></tr>'; And in javascript file I try to execute the following code: function callVehicle(vid) { alert('Call '+vid); document.getElementById("SearchResult").style.visibility="hidden"; } and an error test is not defined occurs. test is the value that I assigned to variable $qry_vehicleid. Can someone please point out what the mistake is?

  Read the article

• PHP user created function return values problem

  - by faX

  Okay I'm new here and I have been trying to figure this out all day I have two functions one calling the other but my functions only returns the last value for example 29 when it should return multiple values. As wondering how can I fix this problem so that my functions return all the values. Here is my PHP code. function parent_comments(){ if(articles_parent_comments_info($_GET['article_id']) !== false){ foreach(articles_parent_comments_info($_GET['article_id']) as $comment_info){ $comment_id = filternum($comment_info['comment_id']); reply_comment_count($comment_id); } } } function reply_comment_count($parent_id){ if(articles_reply_comments_info($_GET['article_id']) !== false){ foreach(articles_reply_comments_info($_GET['article_id']) as $reply_info){ $comment_id = filternum($reply_info['comment_id']); $reply_id = filternum($reply_info['parent_id']); if($parent_id === $reply_id){ reply_comment_count($comment_id); } } } return $comment_id; }

  Read the article

• T-SQL Split String User-Defined Function

  This is open source assembly with function that splits string to parts, which you can deploy at your SQL Server

  Read the article

• dumping the source code for an anonymous function

  - by intuited

  I'm working with a lot of anonymous functions, ie functions declared as part of a dictionary, aka "methods". It's getting pretty painful to debug, because I can't tell what function the errors are happening in. Vim's backtraces look like this: Error detected while processing function NamedFunction..2111..2105: line 1: E730: using List as a String This trace shows that the error occurred in the third level down the stack, on the first line of anonymous function #2105. IE NamedFunction called anonymous function #2111, which called anonymous function #2105. NamedFunction is one declared through the normal function NamedFunction() ... endfunction syntax; the others were declared using code like function dict.func() ... endfunction. So obviously I'd like to find out which function has number 2105. Assuming that it's still in scope, it's possible to find out what Dictionary entry references it by dumping all of the dictionary variables that might contain that reference. This is sort of awkward and it's difficult to be systematic about it, though I guess I could code up a function to search through all of the loaded dictionaries for a reference to that function, watching out for circular references. Although to be really thorough, it would have to search not only script-local and global dictionaries, but buffer-local dictionaries as well; is there a way to access another buffer's local variables? Anyway I'm wondering if it's possible to dump the source code for the anonymous function instead. This would be a lot easier and probably more reliable.

  Read the article

• Given a main function and a cleanup function, how (canonically) do I return an exit status in Bash/Linux?

  - by Zac B

  Context: I have a bash script (a wrapper for other scripts, really), that does the following pseudocode: do a main function if the main function returns: $returncode = $? #most recent return code if the main function runs longer than a timeout: kill the main function $returncode = 140 #the semi-canonical "exceeded allowed wall clock time" status run a cleanup function if the cleanup function returns an error: #nonzero return code exit $? #exit the program with the status returned from the cleanup function else #cleanup was successful .... Question: What should happen after the last line? If the cleanup function was successful, but the main function was not, should my program return 0 (for the successful cleanup), or $returncode, which contains the (possibly nonzero and unsuccessful) return code of the main function? For a specific application, the answer would be easy: "it depends on what you need the script for." However, this is more of a general/canonical question (and if this is the wrong place for it, kill it with fire): in Bash (or Linux in general) programming, do you typically want to return the status that "means" something (i.e. $returncode) or do you ignore such subjectivities and simply return the code of the most recent function? This isn't Bash-specific: if I have a standalone executable of any kind, how, canonically should it behave in these cases? Obviously, this is somewhat debatable. Even if there is a system for these things, I'm sure that a lot of people ignore it. All the same, I'd like to know. Cheers!

  Read the article

• Apples, oranges, and pointers to the most derived c++ class

  - by Matthew Lowe

  Suppose I have a bunch of fruit: class Fruit { ... }; class Apple : public Fruit { ... }; class Orange: public Fruit { ... }; And some polymorphic functions that operate on said fruit: void Eat(Fruit* f, Pesticide* p) { } void Eat(Apple* f, Pesticide* p) { ingest(f,p); } void Eat(Orange* f, Pesticide* p) { peel(f,p); ingest(f,p); } OK, wait. Stop right there. Note at this point that any sane person would make Eat() a virtual member function of the Fruit classes. But that's not an option, because I am not a sane person. Also, I don't want that Pesticide* in the header file for my fruit class. Sadly, what I want to be able to do next is exactly what member functions and dynamic binding allow: typedef list<Fruit*> Fruits; Fruits fs; ... for(Fruits::iterator i=fs.begin(), e=fs.end(); i!=e; ++i) Eat(*i); And obviously, the problem here is that the pointer we pass to Eat() will be a Fruit*, not an Apple* or an Orange*, therefore nothing will get eaten and we will all be very hungry. So what I really want to be able to do instead of this: Eat(*i); is this: Eat(MAGIC_CAST_TO_MOST_DERIVED_CLASS(*i)); But to my limited knowledge, such magic does not exist, except possibly in the form of a big nasty if-statement full of calls to dynamic_cast. So is there some run-time magic of which I am not aware? Or should I implement and maintain a big nasty if-statement full of dynamic_casts? Or should I suck it up, quit thinking about how I would implement this in Ruby, and allow a little Pesticide to make its way into my fruit header?

  Read the article

• How to define and use a friend function to a temlate class with the same template?

  - by Narek

  I have written the following code: #include <iostream> using namespace std; template <class T> class AA { T a; public: AA() { a = 7; } friend void print(const AA<T> & z); }; template <class T> void print(const AA<T> & z) { cout<<"Print: "<<z.a<<endl; } void main() { AA<int> a; print<int>(a); } And getting the following error: error C2248: 'AA<T>::a' : cannot access private member declared in class 'AA<T>' 1> with 1> [ 1> T=int 1> ] 1> c:\users\narek\documents\visual studio 2008\projects\aaa\aaa\a.cpp(7) : see declaration of 'AA<T>::a' 1> with 1> [ 1> T=int 1> ] 1> c:\users\narek\documents\visual studio 2008\projects\aaa\aaa\a.cpp(30) : see reference to function template instantiation 'void print<int>(const AA<T> &)' being compiled 1> with 1> [ 1> T=int 1> ] What's wrong?

  Read the article

• Oracle User definied aggregate function for varray of varchar

  - by baju

  I am trying to write some aggregate function for the varray and I get this error code when I'm trying to use it with data from the DB: ORA-00600 internal error code, arguments: [kodpunp1], [], [], [], [], [], [], [], [], [], [], [] [koxsihread1], [0], [3989], [45778], [], [], [], [], [], [], [], [] Code of the function is really simple(in fact it does nothing ): create or replace TYPE "TEST_VECTOR" as varray(10) of varchar(20) ALTER TYPE "TEST_VECTOR" MODIFY LIMIT 4000 CASCADE create or replace type Test as object( lastVector TEST_VECTOR, STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number, MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number, MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number, MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number ); create or replace type body Test is STATIC FUNCTION ODCIAggregateInitialize(sctx in out Test) return number is begin sctx := Test(TEST_VECTOR()); return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateIterate(self in out Test, value in TEST_VECTOR) return number is begin self.lastVector := value; return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateMerge(self IN OUT Test, ctx2 IN Test) return number is begin return ODCIConst.Success; end; MEMBER FUNCTION ODCIAggregateTerminate(self IN Test, returnValue OUT TEST_VECTOR, flags IN number) return number is begin returnValue := self.lastVector; return ODCIConst.Success; end; end; create or replace FUNCTION test_fn (input TEST_VECTOR) RETURN TEST_VECTOR PARALLEL_ENABLE AGGREGATE USING Test; Next I create some test data: create table t1_test_table( t1_id number not null, t1_value TEST_VECTOR not null, Constraint PRIMARY_KEY_1 PRIMARY KEY (t1_id) ) Next step is to put some data to the table insert into t1_test_table (t1_id,t1_value) values (1,TEST_VECTOR('x','y','z')) Now everything is prepared to perform queries: Select test_fn(TEST_VECTOR('y','x')) from dual Query above work well Select test_fn(t1_value) from t1_test_table where t1_id = 1 Version of Oracle DBMS I use: 11.2.0.3.0 Does anyone tried do such a thing? What can be the reason that it does not work? How to solve it? Thanks in advance for help.

  Read the article

• Declaring an array of character pointers (arg passing)

  - by Isaac Copper

  This is something that should be easy to answer, but is more difficult for me to find a particular right answer on Google or in K&R. I could totally be overlooking this, too, and if so please set me straight! The pertinent code is below: int main(){ char tokens[100][100]; char str = "This is my string"; tokenize(str, tokens); for(int i = 0; i < 100; i++){ printf("%s is a token\n", token[i]); } } void tokenize(char *str, char tokens[][]){ //do stuff with string and tokens, putting //chars into the token array like so: tokens[i][j] = <A CHAR> } So I realize that I can't have char tokens[][] in my tokenize function, but if I put in char **tokens instead, I get a compiler warning. Also, when I try to put a char into my char array with tokens[i][j] = <A CHAR>, I segfault. Where am I going wrong? (And in how many ways... and how can I fix it?) Thanks so much!

  Read the article

• free( ) pointers

  - by user1043625

  I'm required to use a special library to keep track of my memory leaks where malloc()= allocate( ) and free( ) = unallocate( ). I'm trying to complete free a linked-list but it seems like the "root" value isn't being freed. typedef struct _node { struct _node *child; char *command; } Command_list; void delete_commands(Command_list **root) { Command_list *temp; while( *root != NULL ){ temp = (*root)->child; //printf("STRING: %s\n", *root->command ); unallocate( *root ); *root = temp; } } The function that's calling it void file_processing( .... ){ Command_list *root = allocate(sizeof (Command_list)); root = NULL; .... delete_commands( &root ); } } I believe that Command_list *root = allocate(sizeof (Command_list)) isn't being properly de-allocated for some reason. Anyone can give me some hints? UPDATE: I found out that instead of Command_list *root = allocate(sizeof (Command_list)); root = NULL; this works: Command_list *root = NULL;

  Read the article

• Official names for pointer operators

  - by FredOverflow

  What are the official names for the operators * and & in the context of pointers? They seem to be frequently called dereference operator and address-of operator respectively, but unfortunately, the section on unary operators in the standard does not name them. I really don't want to name & address-of anymore, because & returns a pointer, not an address. (A pointer is a language mechanism, while an address is an implementation detail. Addresses are untyped, while pointers aren't, except for void*.) The standard is very clear about this: The result of the unary & operator is a pointer to its operand. Symmetry suggests to name & reference operator which is a little unfortunate because of the collision with references in C++. The fact that & returns a pointer suggests pointer operator. Are there any official sources that would confirm these (or other) namings?

  Read the article

• Converting UnicodeString to PAnsiChar in Delphi XE

  - by moodforaday

  In Delphi XE I am using the BASS audio library, which contains this function: function BASS_StreamCreateURL(url: PAnsiChar; offset: DWORD; flags: DWORD; proc: DOWNLOADPROC; user: Pointer):HSTREAM; stdcall; external bassdll; The 'url' parameter is of type PAnsiChar, so in my code I do a cast: FStreamHandle := BASS_StreamCreateURL(PAnsiChar( url ) [...] The compiler emits a warning on this line: "suspicious typecast of string to PAnsiChar". In trying to eliminate the warning, I found that the recommended way is to use a double cast: FStreamHandle := BASS_StreamCreateURL(PAnsiChar( AnsiString( url )) [...] This does eliminate the warning, but the BASS function now returns error code 2 ("cannot open file"), which tells me the URL string it receives is somehow broken. I cannot see what the bass DLL actually receives, but using a breakpoint in the debugger the string looks good: var s : PAnsiChar; begin s := PAnsiChar( AnsiString( url )); At this point string s appears fine, but the BASS function fails when I pass it. My initial code: PAnsiChar( url ) works well with BASS, but emits a warning. So what's the correct way of getting from UnicodeString to PAnsiChar without a warning?

  Read the article

• How to tell endianness from this output?

  - by Nick Rosencrantz

  I'm running this example program and I'm suppossed to be able to tell from the output what machine type it is. I'm certain it's from inspecting one or two values but how should I perform this inspection? /* pointers.c - Test pointers * Written 2012 by F Lundevall * Copyright abandoned. This file is in the public domain. * * To make this program work on as many systems as possible, * addresses are converted to unsigned long when printed. * The 'l' in formatting-codes %ld and %lx means a long operand. */ #include <stdio.h> #include <stdlib.h> int * ip; /* Declare a pointer to int, a.k.a. int pointer. */ char * cp; /* Pointer to char, a.k.a. char pointer. */ /* Declare fp as a pointer to function, where that function * has one parameter of type int and returns an int. * Use cdecl to get the syntax right, http://cdecl.org/ */ int ( *fp )( int ); int val1 = 111111; int val2 = 222222; int ia[ 17 ]; /* Declare an array of 17 ints, numbered 0 through 16. */ char ca[ 17 ]; /* Declare an array of 17 chars. */ int fun( int parm ) { printf( "Function fun called with parameter %d\n", parm ); return( parm + 1 ); } /* Main function. */ int main() { printf( "Message PT.01 from pointers.c: Hello, pointy World!\n" ); /* Do some assignments. */ ip = &val1; cp = &val2; /* The compiler should warn you about this. */ fp = fun; ia[ 0 ] = 11; /* First element. */ ia[ 1 ] = 17; ia[ 2 ] = 3; ia[ 16 ] = 58; /* Last element. */ ca[ 0 ] = 11; /* First element. */ ca[ 1 ] = 17; ca[ 2 ] = 3; ca[ 16 ] = 58; /* Last element. */ printf( "PT.02: val1: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val1, val1, val1 ); printf( "PT.03: val2: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val2, val2, val2 ); printf( "PT.04: ip: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &ip, (long) ip, (long) ip ); printf( "PT.05: Dereference pointer ip and we find: %d \n", *ip ); printf( "PT.06: cp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &cp, (long) cp, (long) cp ); printf( "PT.07: Dereference pointer cp and we find: %d \n", *cp ); *ip = 1234; printf( "\nPT.08: Executed *ip = 1234; \n" ); printf( "PT.09: val1: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val1, val1, val1 ); printf( "PT.10: ip: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &ip, (long) ip, (long) ip ); printf( "PT.11: Dereference pointer ip and we find: %d \n", *ip ); printf( "PT.12: val1: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val1, val1, val1 ); *cp = 1234; /* The compiler should warn you about this. */ printf( "\nPT.13: Executed *cp = 1234; \n" ); printf( "PT.14: val2: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val2, val2, val2 ); printf( "PT.15: cp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &cp, (long) cp, (long) cp ); printf( "PT.16: Dereference pointer cp and we find: %d \n", *cp ); printf( "PT.17: val2: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val2, val2, val2 ); ip = ia; printf( "\nPT.18: Executed ip = ia; \n" ); printf( "PT.19: ia[0]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ia[0], ia[0], ia[0] ); printf( "PT.20: ia[1]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ia[1], ia[1], ia[1] ); printf( "PT.21: ip: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &ip, (long) ip, (long) ip ); printf( "PT.22: Dereference pointer ip and we find: %d \n", *ip ); ip = ip + 1; /* add 1 to pointer */ printf( "\nPT.23: Executed ip = ip + 1; \n" ); printf( "PT.24: ip: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &ip, (long) ip, (long) ip ); printf( "PT.25: Dereference pointer ip and we find: %d \n", *ip ); cp = ca; printf( "\nPT.26: Executed cp = ca; \n" ); printf( "PT.27: ca[0]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ca[0], ca[0], ca[0] ); printf( "PT.28: ca[1]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ca[1], ca[1], ca[1] ); printf( "PT.29: cp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &cp, (long) cp, (long) cp ); printf( "PT.30: Dereference pointer cp and we find: %d \n", *cp ); cp = cp + 1; /* add 1 to pointer */ printf( "\nPT.31: Executed cp = cp + 1; \n" ); printf( "PT.32: cp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &cp, (long) cp, (long) cp ); printf( "PT.33: Dereference pointer cp and we find: %d \n", *cp ); ip = ca; /* The compiler should warn you about this. */ printf( "\nPT.34: Executed ip = ca; \n" ); printf( "PT.35: ca[0]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ca[0], ca[0], ca[0] ); printf( "PT.36: ca[1]: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &ca[1], ca[1], ca[1] ); printf( "PT.37: ip: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &ip, (long) ip, (long) ip ); printf( "PT.38: Dereference pointer ip and we find: %d \n", *ip ); cp = ia; /* The compiler should warn you about this. */ printf( "\nPT.39: Executed cp = ia; \n" ); printf( "PT.40: cp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &cp, (long) cp, (long) cp ); printf( "PT.41: Dereference pointer cp and we find: %d \n", *cp ); printf( "\nPT.42: fp: stored at %lx (hex); value is %ld (dec), %lx (hex)\n", (long) &fp, (long) fp, (long) fp ); printf( "PT.43: Dereference fp and see what happens.\n" ); val1 = (*fp)(42); printf( "PT.44: Executed val1 = (*fp)(42); \n" ); printf( "PT.45: val1: stored at %lx (hex); value is %d (dec), %x (hex)\n", (long) &val1, val1, val1 ); return( 0 ); } Output Message PT.01 from pointers.c: Hello, pointy World! PT.02: val1: stored at 21e50 (hex); value is 111111 (dec), 1b207 (hex) PT.03: val2: stored at 21e54 (hex); value is 222222 (dec), 3640e (hex) PT.04: ip: stored at 21eb8 (hex); value is 138832 (dec), 21e50 (hex) PT.05: Dereference pointer ip and we find: 111111 PT.06: cp: stored at 21e6c (hex); value is 138836 (dec), 21e54 (hex) PT.07: Dereference pointer cp and we find: 0 PT.08: Executed *ip = 1234; PT.09: val1: stored at 21e50 (hex); value is 1234 (dec), 4d2 (hex) PT.10: ip: stored at 21eb8 (hex); value is 138832 (dec), 21e50 (hex) PT.11: Dereference pointer ip and we find: 1234 PT.12: val1: stored at 21e50 (hex); value is 1234 (dec), 4d2 (hex) PT.13: Executed *cp = 1234; PT.14: val2: stored at 21e54 (hex); value is -771529714 (dec), d203640e (hex) PT.15: cp: stored at 21e6c (hex); value is 138836 (dec), 21e54 (hex) PT.16: Dereference pointer cp and we find: -46 PT.17: val2: stored at 21e54 (hex); value is -771529714 (dec), d203640e (hex) PT.18: Executed ip = ia; PT.19: ia[0]: stored at 21e74 (hex); value is 11 (dec), b (hex) PT.20: ia[1]: stored at 21e78 (hex); value is 17 (dec), 11 (hex) PT.21: ip: stored at 21eb8 (hex); value is 138868 (dec), 21e74 (hex) PT.22: Dereference pointer ip and we find: 11 PT.23: Executed ip = ip + 1; PT.24: ip: stored at 21eb8 (hex); value is 138872 (dec), 21e78 (hex) PT.25: Dereference pointer ip and we find: 17 PT.26: Executed cp = ca; PT.27: ca[0]: stored at 21e58 (hex); value is 11 (dec), b (hex) PT.28: ca[1]: stored at 21e59 (hex); value is 17 (dec), 11 (hex) PT.29: cp: stored at 21e6c (hex); value is 138840 (dec), 21e58 (hex) PT.30: Dereference pointer cp and we find: 11 PT.31: Executed cp = cp + 1; PT.32: cp: stored at 21e6c (hex); value is 138841 (dec), 21e59 (hex) PT.33: Dereference pointer cp and we find: 17 PT.34: Executed ip = ca; PT.35: ca[0]: stored at 21e58 (hex); value is 11 (dec), b (hex) PT.36: ca[1]: stored at 21e59 (hex); value is 17 (dec), 11 (hex) PT.37: ip: stored at 21eb8 (hex); value is 138840 (dec), 21e58 (hex) PT.38: Dereference pointer ip and we find: 185664256 PT.39: Executed cp = ia; PT.40: cp: stored at 21e6c (hex); value is 138868 (dec), 21e74 (hex) PT.41: Dereference pointer cp and we find: 0 PT.42: fp: stored at 21e70 (hex); value is 69288 (dec), 10ea8 (hex) PT.43: Dereference fp and see what happens. Function fun called with parameter 42 PT.44: Executed val1 = (*fp)(42); PT.45: val1: stored at 21e50 (hex); value is 43 (dec), 2b (hex)

  Read the article

• dynamically created arrays

  - by DevAno1

  My task consists of two parts. First I have to create globbal char array of 100 elements, and insert some text to it using cin. Afterwards calculate amount of chars, and create dedicated array with the length of the inputted text. I was thinking about following solution : char[100]inputData; int main() { cin >> inputData >> endl; int length=0; for(int i=0; i<100; i++) { while(inputData[i] == "\0") { ++count; } } char c = new char[count]; Am I thinking good ? Second part of the task is to introduce in the first program dynamically created array of pointers to all inserted words. Adding a new word should print all the previous words and if there is no space for next words, size of the inputData array should be increased twice. And to be honest this is a bit too much for me. How I can create pointers to words specifically ? And how can I increase the size of global array without loosing its content ? With some temporary array ?

  Read the article

• printing reverse in singly link list using pointers

  - by theoneabhinav

  i have been trying this code. i think the logic is ok but the program terminates abruptly when the display_rev function is called here is code of display_rev void display_rev(emp_node *head) { emp_node *p=head, *q; while(p->next != NULL) p=p->next; while(p!=head || p==head){ q=head; display_rec(p); while(q->next != p) q=q->next; p=q; } } here is my whole code #include<stdio.h> #include<stdlib.h> #include<ctype.h> #include<string.h> //Declarations=============================================================== typedef struct //employee record { int emp_id; char name[150]; char mob_no[11]; float salary; int proj[5]; struct emp_node *next; } emp_node; emp_node* add_rec(emp_node*); emp_node* create_db(emp_node*); emp_node* search_db(emp_node*, int); emp_node* delete_rec(emp_node*, int); void read_name(emp_node*); void read_mob(emp_node*); void display_db(emp_node*); void display_rec(emp_node*); void display_rev(emp_node*); void modify_rec(emp_node*); void swtch(emp_node*); //=========================================================================== int main() { char ans; emp_node *head = NULL; head = create_db(head); display_db(head); do { swtch(head); printf("\n\n\tDo you want to continue (y/n) : "); getchar(); scanf("%c", &ans); } while (ans == 'y' || ans == 'Y'); return 0; } //Definitions================================================================ emp_node* create_db(emp_node *head) //database creation { int i = 1, no; emp_node *p; printf("Enter number of employees:"); scanf("%d", &no); printf("\n\n"); head = (emp_node *) malloc(sizeof(emp_node)); head = add_rec(head); head->next = NULL; p = head; while (i < no) { p->next = (emp_node *) malloc(sizeof(emp_node)); p = p->next; p = add_rec(p); p->next = NULL; i++; } return head; } emp_node* add_rec(emp_node *p) //new record { int j; printf("\n\tEmployee ID : "); scanf("%d", &(p->emp_id)); printf("\n\tFirst Name:"); read_name(p); printf("\n\tMobile No.:"); read_mob(p); printf("\n\tSalary :"); scanf("%f", &(p->salary)); printf( "\n\tEnter \"1\" for the projects employee is working on, otherwise enter \"0\": \n"); for (j = 0; j < 5; j++) { printf("\n\t\tProject No. %d : ", j + 1); scanf("%d", &(p->proj[j])); while (p->proj[j] != 1 && p->proj[j] != 0) { printf("\n\nInvalid entry!! Please re-enter."); printf("\n\t\tProject No. %d : ", j + 1); scanf("%d", &(p->proj[j])); } } printf("\n\n\n"); return p; } void read_name(emp_node *p) //validation for name { int j, len; scanf("%s", p->name); len = strlen(p->name); for (j = 0; j < len; j++) { if (!isalpha(p->name[j])) { printf( "\n\n\tInvalid name!!Can contain only characters. Please Re-enter.\n"); printf("\n\tName : "); read_name(p); } } } void read_mob(emp_node *p) //validation for mobile no. { int j; scanf("%s", p->mob_no); while (strlen(p->mob_no) != 10) { printf("\n\nInvalid Mobile No!!Please Re-enter"); printf("\n\n\tMobile No.:"); read_mob(p); } for (j = 0; j < 10; j++) { if (!(48 <= p->mob_no[j] && p->mob_no[j] <= 57)) { printf( "\n\nInvalid Mobile No!!Can contain only digits. Please Re-enter."); printf("\n\n\tMobile No.:"); read_mob(p); } } } void display_db(emp_node *head) //displaying whole database { emp_node *p; p = head; printf("\n\n\t\t****** EMPLOYEE DATABASE ******\n"); printf( "\n=============================================================================="); printf("\n Id.\t Name\t\t Mobile No\t Salary\t Projects\n"); while (p != NULL) { display_rec(p); p = p->next; printf("\n\n\n"); } printf( "\n=============================================================================="); } void swtch(emp_node *head) //function for menu and switch case { int cho, x; emp_node *p; printf("\n\n\t\t****** MENU ******"); printf( "\n\n\t1. insert Record\n\t2. Search Record\n\t3. Modify Record\n\t4. Delete Record\n\t5. Display Reverse\n\t6. Exit"); printf("\n\tWhich operation do you want to perform? "); scanf("%d", &cho); switch (cho) { case 1: p=head; while(p->next != NULL) p=p->next; p->next = (emp_node *) malloc(sizeof(emp_node)); p=p->next; p = add_rec(p); p->next = NULL; display_db(head); break; case 2: printf("\n\n\tEnter employee ID whose record is to be Searched :"); scanf("%d", &x); p = search_db(head, x); if (p == NULL) printf("\n\nRecord not found."); else display_rec(p); break; case 3: printf("\n\n\tEnter employee ID whose record is to be modified :"); scanf("%d", &x); p = search_db(head, x); if (p == NULL) printf("\n\nRecord not found."); else modify_rec(p); display_db(head); break; case 4: printf("\n\n\tEnter employee ID whose record is to be deleted :"); scanf("%d", &x); head = delete_rec(head, x); display_db(head); break; case 5: display_rev(head); case 6: exit(0); default: printf("Invalid Choice!! Please try again."); } } emp_node* search_db(emp_node *head, int id) //search database { emp_node *p = head; while (p != NULL) { if (p->emp_id == id) return p; p = p->next; } return NULL; } void display_rec(emp_node *p) //display a single record { int j; printf("\n %d", p->emp_id); printf("\t %10s", p->name); printf("\t %10s", p->mob_no); printf("\t %05.2f", p->salary); printf("\t "); for (j = 0; j < 5; j++) { if (p->proj[j] == 1) printf(" %d,", j + 1); } } void modify_rec(emp_node *p) //modifying a record { int j, cho; char ch1, edt; do { printf( "\n\t1. Name\n\t2. Email Address\n\t3. Mobile No.\n\t4. Salary\n\t5. Date of birth\n\t6. Projects\n"); printf("Enter your choice : "); scanf("%d", &cho); switch (cho) { case 1: printf("\n\tPrevious name:%s", p->name); printf("\n\tDo you want to edit ? (y/n)"); getchar(); scanf("%c", &ch1); if (ch1 == 'y' || ch1 == 'Y') { printf("\n\tEnter New Name:"); read_name(p); } break; case 2: printf("\n\tPrevious Mobile No. : %s", p->mob_no); printf("\n\tDo you want to edit ? (y/n)"); getchar(); scanf("%c", &ch1); if (ch1 == 'y' || ch1 == 'Y') { printf("\n\tEnter New Mobile No. :"); read_mob(p); } break; case 3: printf("\n\tPrevious salary is : %f", p->salary); printf("\n\tDo you want to edit ? (y/n)"); getchar(); scanf("%c", &ch1); if (ch1 == 'y' || ch1 == 'Y') { printf("\n\tEnter New salary:"); scanf("%f", &(p->salary)); } break; case 4: printf("the employee is currently working on project no. "); for (j = 0; j < 5; j++) { if (p->proj[j] == 1) printf(" %d,", j + 1); } printf("\n\tDo you want to edit ? (y/n)"); getchar(); scanf("%c", &ch1); if (ch1 == 'y' || ch1 == 'Y') { printf( "\n\tEnter \"1\" for the projects employee is working on : \n"); for (j = 0; j < 5; j++) { printf("\n\t\tProject No. %d : ", j + 1); scanf("%d", &(p->proj[j])); while (p->proj[j] != 1) { printf("\n\nInvalid entry!! Please re-enter."); printf("\n\t\tProject No. %d : ", j + 1); scanf("%d", &(p->proj[j])); } } } break; default: printf("\n\nInvalid Choice!! Please Try again."); } printf("\n\nDo you want to edit any other fields ?(y/n)"); getchar(); scanf("%c", &edt); } while (edt == 'y' || edt == 'Y'); } emp_node* delete_rec(emp_node *head, int id) //physical deletion of record { emp_node *p = head, *q; if (head->emp_id == id) { head = head->next; free(p); return head; } else { q = p->next; while (q->emp_id != id) { p = p->next; q = q->next; } if (q->next == NULL) p->next = NULL; else p->next = q->next; free(q); return head; } } void display_rev(emp_node *head) { emp_node *p=head, *q; while(p->next != NULL) p=p->next; while(p!=head || p==head){ q=head; display_rec(p); while(q->next != p) q=q->next; p=q; } }

  Read the article

• Polymorphic Queue

  - by metdos

  Hello Everyone, I'm trying to implement a Polymorphic Queue. Here is my trial: QQueue <Request *> requests; while(...) { QString line = QString::fromUtf8(client->readLine()).trimmed(); if(...)){ Request *request=new Request(); request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); //this initialize variables in request using tcpMessage if(request->requestType==REQUEST_LOGIN){ LoginRequest loginRequest; request=&loginRequest; request->tcpMessage=line.toUtf8(); request->decodeFromTcpMessage(); requests.enqueue(request); } //Here pointers in "requests" do not point to objects I created above, and I noticed that their destructors are also called. LoginRequest *loginRequest2=dynamic_cast<LoginRequest *>(requests.dequeue()); loginRequest2->decodeFromTcpMessage(); } } Unfortunately, I could not manage to make work Polymorphic Queue with this code because of the reason I mentioned in second comment.I guess, I need to use smart-pointers, but how? I'm open to any improvement of my code or a new implementation of polymorphic queue. Thanks.

  Read the article

• Getting value from pointer

  - by Eric

  Hi, I'm having problem getting the value from a pointer. I have the following code in C++: void* Nodo::readArray(VarHash& var, string varName, int posicion, float& d) { //some code before... void* res; float num = bit.getFloatFromArray(arregloTemp); //THIS FUNCTION RETURN A FLOAT AND IT'S OK cout << "NUMBER " << num << endl; d = num; res = &num; return res } int main() { float d = 0.0; void* res = n.readArray(v, "c", 0, d); //THE VALUES OF THE ARRAY ARE: {65.5, 66.5}; float* car3 = (float*)res; cout << "RESULT_READARRAY " << *car3 << endl; cout << "FLOAT REFERENCE: " << d << endl; } The result of running this code is the following: NUMBER 65.5 RESULT_READARRAY -1.2001 //INCORRECT IT SHOULD BE LIKE NUMBER FLOAT REFERENCE: 65.5 //CORRECT NUMBER 66.5 RESULT_READARRAY -1.2001 //INCORRECT IT SHOULD BE LIKE NUMBER FLOAT REFERENCE: 66.5 //CORRECT For some reason, when I get the value of the pointer returned by the function called readArray is incorrect. I'm passing a float variable(d) as a reference in the same function just to verify that the value is ok, and as you can see, THE FLOAT REFERENCE matches the NUMBER. If I declare the variable num(read array) as a static float, the first RESULT_READARRAY will be 65.5, that is correct, however, the next value will be the same instead of 66.5. Let me show you the result of running the code using static float variable: NUMBER 65.5 RESULT_READARRAY 65.5 //PERFECT FLOAT REFERENCE: 65.5 //¨PERFECT NUMBER 65.5 //THIS IS INCORRECT, IT SHOULD BE 66.5 RESULT_READARRAY 65.5 FLOAT REFERENCE: 65.5 Do you know how can I get the correct value returned by the function called readArray()?

  Read the article

• C++ - passing references to boost::shared_ptr

  - by abigagli

  If I have a function that needs to work with a shared_ptr, wouldn't it be more efficient to pass it a reference to it (so to avoid copying the shared_ptr object)? What are the possible bad side effects? I envision two possible cases: 1) inside the function a copy is made of the argument, like in ClassA::take_copy_of_sp(boost::shared_ptr<foo> &sp) { ... m_sp_member=sp; //This will copy the object, incrementing refcount ... } 2) inside the function the argument is only used, like in Class::only_work_with_sp(boost::shared_ptr<foo> &sp) //Again, no copy here { ... sp->do_something(); ... } I can't see in both cases a good reason to pass the boost::shared_ptr by value instead of by reference. Passing by value would only "temporarily" increment the reference count due to the copying, and then decrement it when exiting the function scope. Am I overlooking something? Andrea. EDIT: Just to clarify, after reading several answers : I perfectly agree on the premature-optimization concerns, and I alwasy try to first-profile-then-work-on-the-hotspots. My question was more from a purely technical code-point-of-view, if you know what I mean.

  Read the article

• Does it exist: smart pointer, owned by one object allowing access.

  - by Noah Roberts

  I'm wondering if anyone's run across anything that exists which would fill this need. Object A contains an object B. It wants to provide access to that B to clients through a pointer (maybe there's the option it could be 0, or maybe the clients need to be copiable and yet hold references...whatever). Clients, lets call them object C, would normally, if we're perfect developers, be written carefully so as to not violate the lifetime semantics of any pointer to B they might have...but we're not perfect, in fact we're pretty dumb half the time. So what we want is for object C to have a pointer to object B that is not "shared" ownership but that is smart enough to recognize a situation in which the pointer is no longer valid, such as when object A is destroyed or it destroys object B. Accessing this pointer when it's no longer valid would cause an assertion/exception/whatever. In other words, I wish to share access to data in a safe, clear way but retain the original ownership semantics. Currently, because I've not been able to find any shared pointer in which one of the objects owns it, I've been using shared_ptr in place of having such a thing. But I want clear owneship and shared/weak pointer doesn't really provide that. Would be nice further if this smart pointer could be attached to member variables and not just hold pointers to dynamically allocated memory regions. If it doesn't exist I'm going to make it, so I first want to know if someone's already released something out there that does it. And, BTW, I do realize that things like references and pointers do provide this sort of thing...I'm looking for something smarter.

  Read the article

• Isn't an Iterator in c++ a kind of a pointer?

  - by Bilthon

  Ok this time I decided to make a list using the STL. I need to create a dedicated TCP socket for each client. So everytime I've got a connection, I instantiate a socket and add a pointer to it on a list. list<MyTcp*> SocketList; //This is the list of pointers to sockets list<MyTcp*>::iterator it; //An iterator to the list of pointers to TCP sockets. Putting a new pointer to a socket was easy, but now every time the connection ends I should disconnect the socket and delete the pointer so I don't get a huge memory leak, right? well.. I thought I was doing ok by setting this: it=SocketList.begin(); while( it != SocketList.end() ){ if((*it)->getClientId() == id){ pSocket = it; // <-------------- compiler complains at this line SocketList.remove(pSocket); pSocket->Disconnect(); delete pSocket; break; } } But the compiler is saying this: error: invalid cast from type ‘std::_List_iterator<MyTcp*>’ to type ‘MyTcp*’ Can someone help me here? i thought I was doing things right, isn't an iterator at any given time just pointing to one of the elements of the set? how can I fix it?

  Read the article

< Previous Page | 40 41 42 43 44 45 46 47 48 49 50 51  | Next Page >