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  • Multiple constructors in C

    - by meepz
    Hello, I am making a string class in C as a homework and I was wondering how I can make multiple constructors with the same name given the parameter. The commented out area is what I tried to do with results from a few searches but that gives me errors. Pretty much I have some cases where I want to create my new string without any parameter then in other cases create a string with a pointer to character. Here is mystring.h #include <stdio.h> #include <stdlib.h> typedef struct mystring { char * c; int length; int (*sLength)(void * s); char (*charAt)(void * s, int i); int (*compareTo)(void * s1, void * s2); struct mystring * (*concat)(void * s1, void * s2); struct mystring * (*subString)(void * s, int begin, int end); void (*printS)(void * s); } string_t; typedef string_t * String; String newString(char * c); String newString2(); int slength(void * s); char charat(void * S, int i); int compareto(void * s1, void * s2); String concat(void * s1, void * s2); String substring(void * S, int begin, int end); void printstring(void * s); And here is mystring.c #include "mystring.h" String newString(){ } String newString(char * input){ //String newString::newString(char * input) { String s; s = (string_t *) malloc(sizeof(string_t)); s->c = (char *) malloc(sizeof(char) * 20); int i = 0; if (input == NULL){ s->c[0] = '\0'; return s; } while (input[i] != '\0') { s->c[i] = input[i]; i++; } //functions s->sLength = slength; s->charAt = charat; s->compareTo = compareto; s->concat = concat; s->subString = substring; s->printS = printstring; return s; }

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  • C++ "if then else" template substitution

    - by duli
    I would like to declare a template as follows: template <typename T> { if objects of class T have method foo(), then const int k=1 else if class has a static const int L then const int k=L else const int k=0; } How can I do this? In general, I would like a mechanism for setting static consts based on properties of T (or typedef defined inside T).

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  • How to use mmap to point to STL type?

    - by srikfreak
    I have a mmap typecast to a char pointer char *ptr; ptr = (char *)mmap(0, FILESIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); This was my earlier code. But now I want to use a map instead of char * as the requirements changed. Now, my map is declared as map i_s_map; How do I change my mmap call to point to the map?

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  • conversion of DNA to Protein - c structure issue

    - by sam
    I am working on conversion of DNA sequence to Protein sequence. I had completed all program only one error I found there is of structure. dna_codon is a structure and I am iterating over it.In first iteration it shows proper values of structure but from next iteration, it dont show the proper value stored in structure. Its a small error so do not think that I havnt done anything and downvote. I am stucked here because I am new in c for structures. CODE : #include <stdio.h> #include<string.h> void main() { int i, len; char short_codons[20]; char short_slc[1000]; char sequence[1000]; struct codons { char amino_acid[20], slc[20], dna_codon[40]; }; struct codons c1 [20]= { {"Isoleucine", "I", "ATT, ATC, ATA"}, {"Leucine", "L", "CTT, CTC, CTA, CTG, TTA, TTG"}, {"Valine", "V", "GTT, GTC, GTA, GTG"}, {"Phenylalanine", "F", "TTT, TTC"}, {"Methionine", "M", "ATG"}, {"Cysteine", "C", "TGT, TGC"}, {"Alanine", "A", "GCT, GCC, GCA, GCG"}, {"Proline", "P", "CCT, CCC, CCA,CCG "}, {"Threonine", "T", "ACT, ACC, ACA, ACG"}, {"Serine", "S", "TCT, TCC, TCA, TCG, AGT, AGC"}, {"Tyrosine", "Y", "TAT, TAC"}, {"Tryptophan", "W", "TGG"}, {"Glutamine", "Q", "CAA, CAG"}, {"Aspargine","N" "AAT, AAC"}, {"Histidine", "H", "CAT, CAC"}, {"Glutamic acid", "E", "GAA, GAG"}, {"Aspartic acid", "D", "GAT, GAC"}, {"Lysine", "K", "AAA, AAG"}, {"Arginine", "R", "CGT, CGC, CGA, CGG, AGA, AGG"}, {"Stop codons", "Stop", "AA, TAG, TGA"} }; int count = 0; printf("Enter the sequence: "); gets(sequence); char *input_string = sequence; char *tmp_str = input_string; int k; char *pch; while (*input_string != '\0') { char string_3l[4] = {'\0'}; strncpy(string_3l, input_string, 3); printf("\n-----------%s & %s----------", string_3l, tmp_str ); for(k=0;k<20;k++) { //printf("@REAL - %s", c1[0].dna_codon); printf("@ %s", c1[k].dna_codon); int x; x = c1[k].dna_codon; pch = strtok(x, ","); while (pch != NULL) { printf("\n%d : %s with %s", k, string_3l, pch); count=strcmp(string_3l, pch); if(count==0) { strcat(short_slc, c1[k].slc); printf("\n==>%s", short_slc); } pch = strtok (NULL, " ,.-"); } } input_string = input_string+3; } printf("\nProtien sequence is : %s\n", short_slc); } INPUT : TAGTAG OUTPUT : If you see output of printf("\n-----------%s & %s----------", string_3l, tmp_str ); in both iterations, we found that values defined in structure are reduced. I want to know why structure reduces it or its my mistake? because I am stucked here

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  • Overloading assignment operator in C++

    - by jasonline
    As I've understand, when overloading operator=, the return value should should be a non-const reference. A& A::operator=( const A& ) { // check for self-assignment, do assignment return *this; } It is non-const to allow non-const member functions to be called in cases like: ( a = b ).f(); But why should it return a reference? In what instance will it give a problem if the return value is not declared a reference, let's say return by value?

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  • Why can't I add pointers

    - by Knowing me knowing you
    Having very similiar code like so: LINT_rep::Iterator::difference_type LINT_rep::Iterator::operator+(const Iterator& right)const { return (this + &right);//IN THIS PLACE I'M GETTING AN ERROR } LINT_rep::Iterator::difference_type LINT_rep::Iterator::operator-(const Iterator& right)const {//substracts one iterator from another return (this - &right);//HERE EVERYTHING IS FINE } err msg: Error 1 error C2110: '+' : cannot add two pointers Why I'm getting an err in one place and not in both?

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  • operator+ overload returning object causing memory leaks, C++

    - by lampshade
    The problem i think is with returing an object when i overload the + operator. I tried returning a reference to the object, but doing so does not fix the memory leak. I can comment out the two statements: dObj = dObj + dObj2; and cObj = cObj + cObj2; to free the program of memory leaks. Somehow, the problem is with returning an object after overloading the + operator. #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); Dog operator+(const Dog &dObj); private : char * name; char * gender; int age; }; class MyClass { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); private : Animal * action; }; Dog::Dog(const char * name, const char * gender, int age) : // allocating here, for data passed in ctor name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } Dog Dog::operator+(const Dog &dObj) { Dog d; d.age = age + dObj.age; return d; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } int main() { MyClass mObj; Dog dObj("Scruffy", "Male", 4); // passing data into ctor Dog dObj2("Scooby", "Male", 6); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj = dObj + dObj2; // invoke the operator+ return 0; }

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  • Text Obfuscation using base64_encode()

    - by user271619
    I'm playing around with encrypt/decrypt coding in php. Interesting stuff! However, I'm coming across some issues involving what text gets encrypted into. Here's 2 functions that encrypt and decrypt a string. It uses an Encryption Key, which I set as something obscure. I actually got this from a php book. I modified it slightly, but not to change it's main goal. I created a small example below that anyone can test. But, I notice that some characters show up as the "encrypted" string. Characters like "=" and "+". Sometimes I pass this encrypted string via the url. Which may not quite make it to my receiving scripts. I'm guessing the browser does something to the string if certain characters are seen. I'm really only guessing. is there another function I can use to ensure the browser doesn't touch the string? or does anyone know enough php bas64_encode() to disallow certain characters from being used? I'm really not going to expect the latter as a possibility. But, I'm sure there's a work-around. enjoy the code, whomever needs it! define('ENCRYPTION_KEY', "sjjx6a"); function encrypt($string) { $result = ''; for($i=0; $i<strlen($string); $i++) { $char = substr($string, $i, 1); $keychar = substr(ENCRYPTION_KEY, ($i % strlen(ENCRYPTION_KEY))-1, 1); $char = chr(ord($char)+ord($keychar)); $result.=$char; } return base64_encode($result)."/".rand(); } function decrypt($string){ $exploded = explode("/",$string); $string = $exploded[0]; $result = ''; $string = base64_decode($string); for($i=0; $i<strlen($string); $i++) { $char = substr($string, $i, 1); $keychar = substr(ENCRYPTION_KEY, ($i % strlen(ENCRYPTION_KEY))-1, 1); $char = chr(ord($char)-ord($keychar)); $result.=$char; } return $result; } echo $encrypted = encrypt("reaplussign.jpg"); echo "<br>"; echo decrypt($encrypted);

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  • Can't find mistake -- 'segmentation fault' - in C

    - by Mosh
    Hello all! I wrote this function but can't get on the problem that gives me 'segmentation fault' msg. Thank you for any help guys !! /*This function extract all header files in a *.c1 file*/ void includes_extractor(FILE *c1_fp, char *c1_file_name ,int c1_file_str_len ) { int i=0; FILE *c2_fp , *header_fp; char ch, *c2_file_name,header_name[80]; /* we can assume line length 80 chars MAX*/ char inc_name[]="include"; char inc_chk[INCLUDE_LEN+1]; /*INCLUDE_LEN is defined | +1 for null*/ /* making the c2 file name */ c2_file_name=(char *) malloc ((c1_file_str_len)*sizeof(char)); if (c2_file_name == NULL) { printf("Out of memory !\n"); exit(0); } strcpy(c2_file_name , c1_file_name); c2_file_name[c1_file_str_len-1] = '\0'; c2_file_name[c1_file_str_len-2] = '2'; /*Open source & destination files + ERR check */ if( !(c1_fp = fopen (c1_file_name,"r") ) ) { fprintf(stderr,"\ncannot open *.c1 file !\n"); exit(0); } if( !(c2_fp = fopen (c2_file_name,"w+") ) ) { fprintf(stderr,"\ncannot open *.c2 file !\n"); exit(0); } /*next code lines are copy char by char from c1 to c2, but if meet header file, copy its content */ ch=fgetc(c1_fp); while (!feof(c1_fp)) { i=0; /*zero i */ if (ch == '#') /*potential #include case*/ { fgets(inc_chk, INCLUDE_LEN+1, c1_fp); /*8 places for "include" + null*/ if(strcmp(inc_chk,inc_name)==0) /*case #include*/ { ch=fgetc(c1_fp); while(ch==' ') /* stop when head with a '<' or '"' */ { ch=fgetc(c1_fp); } /*while(2)*/ ch=fgetc(c1_fp); /*start read header file name*/ while((ch!='"') || (ch!='>')) /*until we get the end of header name*/ { header_name[i] = ch; i++; ch=fgetc(c1_fp); }/*while(3)*/ header_name[i]='\0'; /*close the header_name array*/ if( !(header_fp = fopen (header_name,"r") ) ) /*open *.h for read + ERR chk*/ { fprintf(stderr,"cannot open header file !\n"); exit(0); } while (!feof(header_fp)) /*copy header file content to *.c2 file*/ { ch=fgetc(header_fp); fputc(ch,c2_fp); }/*while(4)*/ fclose(header_fp); } }/*frst if*/ else { fputc(ch,c2_fp); } ch=fgetc(c1_fp); }/*while(1)*/ fclose(c1_fp); fclose(c2_fp); free (c2_file_name); }

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  • Optimizing sorting container of objects with heap-allocated buffers - how to avoid hard-copying buff

    - by Kache4
    I was making sure I knew how to do the op= and copy constructor correctly in order to sort() properly, so I wrote up a test case. After getting it to work, I realized that the op= was hard-copying all the data_. I figure if I wanted to sort a container with this structure (its elements have heap allocated char buffer arrays), it'd be faster to just swap the pointers around. Is there a way to do that? Would I have to write my own sort/swap function? #include <deque> //#include <string> //#include <utility> //#include <cstdlib> #include <cstring> #include <iostream> //#include <algorithm> // I use sort(), so why does this still compile when commented out? #include <boost/filesystem.hpp> #include <boost/foreach.hpp> using namespace std; namespace fs = boost::filesystem; class Page { public: // constructor Page(const char* path, const char* data, int size) : path_(fs::path(path)), size_(size), data_(new char[size]) { // cout << "Creating Page..." << endl; strncpy(data_, data, size); // cout << "done creating Page..." << endl; } // copy constructor Page(const Page& other) : path_(fs::path(other.path())), size_(other.size()), data_(new char[other.size()]) { // cout << "Copying Page..." << endl; strncpy(data_, other.data(), size_); // cout << "done copying Page..." << endl; } // destructor ~Page() { delete[] data_; } // accessors const fs::path& path() const { return path_; } const char* data() const { return data_; } int size() const { return size_; } // operators Page& operator = (const Page& other) { if (this == &other) return *this; char* newImage = new char[other.size()]; strncpy(newImage, other.data(), other.size()); delete[] data_; data_ = newImage; path_ = fs::path(other.path()); size_ = other.size(); return *this; } bool operator < (const Page& other) const { return path_ < other.path(); } private: fs::path path_; int size_; char* data_; }; class Book { public: Book(const char* path) : path_(fs::path(path)) { cout << "Creating Book..." << endl; cout << "pushing back #1" << endl; pages_.push_back(Page("image1.jpg", "firstImageData", 14)); cout << "pushing back #3" << endl; pages_.push_back(Page("image3.jpg", "thirdImageData", 14)); cout << "pushing back #2" << endl; pages_.push_back(Page("image2.jpg", "secondImageData", 15)); cout << "testing operator <" << endl; cout << pages_[0].path().string() << (pages_[0] < pages_[1]? " < " : " > ") << pages_[1].path().string() << endl; cout << pages_[1].path().string() << (pages_[1] < pages_[2]? " < " : " > ") << pages_[2].path().string() << endl; cout << pages_[0].path().string() << (pages_[0] < pages_[2]? " < " : " > ") << pages_[2].path().string() << endl; cout << "sorting" << endl; BOOST_FOREACH (Page p, pages_) cout << p.path().string() << endl; sort(pages_.begin(), pages_.end()); cout << "done sorting\n"; BOOST_FOREACH (Page p, pages_) cout << p.path().string() << endl; cout << "checking datas" << endl; BOOST_FOREACH (Page p, pages_) { char data[p.size() + 1]; strncpy((char*)&data, p.data(), p.size()); data[p.size()] = '\0'; cout << p.path().string() << " " << data << endl; } cout << "done Creating Book" << endl; } private: deque<Page> pages_; fs::path path_; }; int main() { Book* book = new Book("/some/path/"); }

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  • Why wont my while loop take new input (c++)

    - by Van
    I've written a program to get a string input from a user and parse it into tokens and move a robot according to the input. My problem is trying to issue more than one command. The code looks like: void Navigator::manualDrive() { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; while(true) { Navigator::parseInstruction(uinput); } } /* parseInstruction(char *c) -- parses cstring instructions received * and moves robot accordingly */ void Navigator::parseInstruction(char * c) { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; cout << "Enter your directions below: \n"; cin.ignore(); cin.getline (uinput, bufSize); token=strtok(uinput, delim); if(strcmp("forward", token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); Navigator::travel(inches); } if(strcmp("back",token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); double value = fabs(0.0735 * fabs(inches) - 0.0550); myRobot.backward(1/*speed*/, value/*time*/); } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("left",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnLeft(1/*speed*/, value/*time*/); } } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("right",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnRight(1/*speed*/, value/*time*/); } } if(strcmp("stop",token) == 0) { myRobot.motors(0,0); } } In the function manualDrive I have a while loop calling the function parseInstruction infinitely. The program outputs "Enter your directions below: " When I give the program instructions it executes them, and then it outputs "enter your directions below: " again and when I input my directions again it does not execute them and outputs "Enter your directions below: " instead. I'm sure this is a very simple fix I'm just very new to c++. So if you could please help me out and tell me why the program only takes the first set of directions. thanks

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  • Problem separating C++ code in header, inline functions and code.

    - by YuppieNetworking
    Hello all, I have the simplest code that I want to separate in three files: Header file: class and struct declarations. No implementations at all. Inline functions file: implementation of inline methods in header. Code file: normal C++ code for more complicated implementations. When I was about to implement an operator[] method, I couldn't manage to compile it. Here is a minimal example that shows the same problem: Header (myclass.h): #ifndef _MYCLASS_H_ #define _MYCLASS_H_ class MyClass { public: MyClass(const int n); virtual ~MyClass(); double& operator[](const int i); double operator[](const int i) const; void someBigMethod(); private: double* arr; }; #endif /* _MYCLASS_H_ */ Inline functions (myclass-inl.h): #include "myclass.h" inline double& MyClass::operator[](const int i) { return arr[i]; } inline double MyClass::operator[](const int i) const { return arr[i]; } Code (myclass.cpp): #include "myclass.h" #include "myclass-inl.h" #include <iostream> inline MyClass::MyClass(const int n) { arr = new double[n]; } inline MyClass::~MyClass() { delete[] arr; } void MyClass::someBigMethod() { std::cout << "Hello big method that is not inlined" << std::endl; } And finally, a main to test it all: #include "myclass.h" #include <iostream> using namespace std; int main(int argc, char *argv[]) { MyClass m(123); double x = m[1]; m[1] = 1234; cout << "m[1]=" << m[1] << endl; x = x + 1; return 0; } void nothing() { cout << "hello world" << endl; } When I compile it, it says: main.cpp:(.text+0x1b): undefined reference to 'MyClass::MyClass(int)' main.cpp:(.text+0x2f): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x49): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x65): undefined reference to 'MyClass::operator[](int)' However, when I move the main method to the MyClass.cpp file, it works. Could you guys help me spot the problem? Thank you.

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  • Esoteric C++ operators

    - by Neil G
    What is the purpose of the following esoteric C++ operators? Pointer to member ::* Bind pointer to member by pointer ->* Bind pointer to member by reference .* (reference)

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  • Why wont my while loop wont take new input (c++)

    - by Van
    I've written a program to get a string input from a user and parse it into tokens and move a robot according to the input. My problem is trying to issue more than one command. The code looks like: void Navigator::manualDrive() { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; while(true) { Navigator::parseInstruction(uinput); } } /* parseInstruction(char *c) -- parses cstring instructions received * and moves robot accordingly */ void Navigator::parseInstruction(char * c) { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; cout << "Enter your directions below: \n"; cin.ignore(); cin.getline (uinput, bufSize); token=strtok(uinput, delim); if(strcmp("forward", token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); Navigator::travel(inches); } if(strcmp("back",token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); double value = fabs(0.0735 * fabs(inches) - 0.0550); myRobot.backward(1/*speed*/, value/*time*/); } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("left",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnLeft(1/*speed*/, value/*time*/); } } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("right",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnRight(1/*speed*/, value/*time*/); } } if(strcmp("stop",token) == 0) { myRobot.motors(0,0); } } In the function manualDrive I have a while loop calling the function parseInstruction infinitely. The program outputs "Enter your directions below: " When I give the program instructions it executes them, and then it outputs "enter your directions below: " again and when I input my directions again it does not execute them and outputs "Enter your directions below: " instead. I'm sure this is a very simple fix I'm just very new to c++. So if you could please help me out and tell me why the program only takes the first set of directions. thanks

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  • weird performance in C++ (VC 2010)

    - by raicuandi
    Hello, I have this loop written in C++, that compiled with MSVC2010 takes a long time to run. (300ms) for (int i=0; i<h; i++) { for (int j=0; j<w; j++) { if (buf[i*w+j] > 0) { const int sy = max(0, i - hr); const int ey = min(h, i + hr + 1); const int sx = max(0, j - hr); const int ex = min(w, j + hr + 1); float val = 0; for (int k=sy; k < ey; k++) { for (int m=sx; m < ex; m++) { val += original[k*w + m] * ds[k - i + hr][m - j + hr]; } } heat_map[i*w + j] = val; } } } It seemed a bit strange to me, so I did some tests then changed a few bits to inline assembly: (specifically, the code that sums "val") for (int i=0; i<h; i++) { for (int j=0; j<w; j++) { if (buf[i*w+j] > 0) { const int sy = max(0, i - hr); const int ey = min(h, i + hr + 1); const int sx = max(0, j - hr); const int ex = min(w, j + hr + 1); __asm { fldz } for (int k=sy; k < ey; k++) { for (int m=sx; m < ex; m++) { float val = original[k*w + m] * ds[k - i + hr][m - j + hr]; __asm { fld val fadd } } } float val1; __asm { fstp val1 } heat_map[i*w + j] = val1; } } } Now it runs in half the time, 150ms. It does exactly the same thing, but why is it twice as quick? In both cases it was run in Release mode with optimizations on. Am I doing anything wrong in my original C++ code?

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  • infix operation to postfix using stacks

    - by Chris De La O
    We are writing a program that needs to convert an infix operation (4 5/3) to postfix (4 5 3 / ) using stacks. however my convert to postfix does not work as it doesnt not output the postFix array that is supposed to store the conversion from infix notation to postfix notation. here is the code for the convertToPostix fuction. //converts infix expression to postfix expression void ArithmeticExpression::convertToPostfix(char *const inFix, char *const postFix) { //create a stack2 object named cow Stack2<char> cow; cout<<postFix; char thing = '('; //push a left parenthesis onto the stack cow.push(thing); //append a right parenthesis to the end of inFix array strcat(inFix, ")"); int i = 0;//declare an int that will control posFix position //if the stack is not empty if (!cow.isEmpty()) { //loop to run until the last character in inFix array for (int x = 0; inFix[x]!= '\0'; x++ ) { //if the inFix element is a digit if (isdigit(inFix[x])) { postFix[i]=inFix[x];//it is assigned to the next element in postFix array i++;//move on to next element in postFix } //if the inFix element is a left parenthesis else if (inFix[x]=='(') { cow.push(inFix[x]);//push it unto the stack } //if the inFix element is an operator else if (isOperator(inFix[x])) { char oper2 = inFix[x];//char variable holds inFix operator if (isOperator(cow.stackTop()))//if the top node in the stack is an operator { while (isOperator(cow.stackTop()))//and while the top node in the stack is an operator { char oper1 = cow.stackTop();//char variable holds node operator if(precedence( oper1, oper2))//if the node operator has higher presedence than node operator { postFix[i] = cow.pop();//we pop such operator and insert it in postFix array's next element cow.push(inFix[x]);//and push inFix operator unto the stack i++;//move to the next element in posFix } } } //if the top node is not an operator //we push the current inFix operator unto the top of the stack else cow.push(inFix[x]); } //if the inFix element is a right parenthesis else if (inFix[x]==')') { //we pop everything in the stack and insert it in postFix //until we arrive at a left paranthesis while (cow.stackTop()!='(') { postFix[i] = cow.pop(); i++; } //we then pop and discard left parenthesis cow.pop(); } } postFix[i]='\0'; //print !!postFix array!! (not stack) print();//code for this is just cout<<postFix; }

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  • Basic data alignment question

    - by Broken Logic
    I've been playing around to see how my computer works under the hood. What I'm interested in is seeing is what happens on the stack inside a function. To do this I've written the following toy program: #include <stdio.h> void __cdecl Test1(char a, unsigned long long b, char c) { char c1; unsigned long long b1; char a1; c1 = 'b'; b1 = 4; a1 = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&b1 - (long)&a1, (long)&c1 - (long)&b1, (long)&a - (long)&c1, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&a1 ); }; struct TestStruct { char a; unsigned long long b; char c; }; void __cdecl Test2(char a, unsigned long long b, char c) { TestStruct locals; locals.a = 'b'; locals.b = 4; locals.c = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&locals.b - (long)&locals.a, (long)&locals.c - (long)&locals.b, (long)&a - (long)&locals.c, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&locals.a ); }; int main() { Test1('f', 0, 'o'); Test2('f', 0, 'o'); return 0; } And this spits out the following: 9 19 - 13 - 4 8 Total: 53 8 8 - 24 - 4 8 Total: 52 The function args are well behaved but as the calling convention is specified, I'd expect this. But the local variables are a bit wonky. My question is, why wouldn't these be the same? The second call seems to produce a more compact and better aligned stack. Looking at the ASM is unenlightening (at least to me), as the variable addresses are still aliased there. So I guess this is really a question about the assembler itself allocates the stack to local variables. I realise that any specific answer is likely to be platform specific. I'm more interested in a general explanation unless this quirk really is platform specific. For the record though, I'm compiling with VS2010 on a 64bit Intel machine.

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  • Types questions in ANSI C

    - by shaharg
    Hi, I having few questions about typed in ANSI C: 1. what's the difference between "\x" in the beginning of a char to 0x in the beginning of char (or in any other case for this matter). AFAIK, they both means that this is hexadecimal.. so what's the difference. when casting char to (unsigned), not (unsigned char) - what does it mean? why (unsigned)'\xFF' != 0xFF? Thanks!

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  • C socket programming: select() is returning 0 despite messages sent from server

    - by Fantastic Fourier
    Hey all, I'm using select() to recv() messages from server, using TCP/IP. When I send() messages from the server, it returns a reasonable number of bytes, saying it's sent successful. And it does get to the client successfully when I use while loop to just recv(). Everything is fine and dandy. while(1) recv() // obviously pseudocode However, when I try to use select(), select() returns 0 from timeout (which is set to 1 second) and for the life of me I cannot figure out why it doesn't see the messages sent from the server. I should also mention that when the server disconnects, select() doesn't see that either, where as if I were to use recv(), it would return 0 to indicate that the connection using the socket has been closed. Any inputs or thoughts are deeply appreciated. #include <arpa/inet.h> #include <errno.h> #include <fcntl.h> #include <netdb.h> #include <netinet/in.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include <sys/select.h> #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <time.h> #include <unistd.h> #define SERVER_PORT 10000 #define MAX_CONNECTION 20 #define MAX_MSG 50 struct client { char c_name[MAX_MSG]; char g_name[MAX_MSG]; int csock; int host; // 0 = not host of a multicast group struct sockaddr_in client_address; struct client * next_host; struct client * next_client; }; struct fd_info { char c_name[MAX_MSG]; int socks_inuse[MAX_CONNECTION]; int sock_fd, max_fd; int exit; struct client * c_sys; struct sockaddr_in c_address[MAX_CONNECTION]; struct sockaddr_in server_address; struct sockaddr_in client_address; fd_set read_set; }; struct message { char c_name[MAX_MSG]; char g_name[MAX_MSG]; char _command[3][MAX_MSG]; char _payload[MAX_MSG]; struct sockaddr_in client_address; struct client peer; }; int main(int argc, char * argv[]) { char * host; char * temp; int i, sockfd; int msg_len, rv, ready; int connection, management, socketread; int sockfds[MAX_CONNECTION]; // for three threads that handle new connections, user inputs and select() for sockets pthread_t connection_handler, manager, socket_reader; struct sockaddr_in server_address, client_address; struct hostent * hserver, cserver; struct timeval timeout; struct message msg; struct fd_info info; info.exit = 0; // exit information: if exit = 1, threads quit info.c_sys = NULL; // looking up from the host database if (argc == 3) { host = argv[1]; // server address strncpy(info.c_name, argv[2], strlen(argv[2])); // client name } else { printf("plz read the manual, kthxbai\n"); exit(1); } printf("host is %s and hp is %p\n", host, hserver); hserver = gethostbyname(host); if (hserver) { printf("host found: %s\n", hserver->h_name ); } else { printf("host not found\n"); exit(1); } // setting up address and port structure information on serverside bzero((char * ) &server_address, sizeof(server_address)); // copy zeroes into string server_address.sin_family = AF_INET; memcpy(&server_address.sin_addr, hserver->h_addr, hserver->h_length); server_address.sin_port = htons(SERVER_PORT); bzero((char * ) &client_address, sizeof(client_address)); // copy zeroes into string client_address.sin_family = AF_INET; client_address.sin_addr.s_addr = htonl(INADDR_ANY); client_address.sin_port = htons(SERVER_PORT); // opening up socket sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) exit(1); else { printf("socket is opened: %i \n", sockfd); info.sock_fd = sockfd; } // sets up time out option for the bound socket timeout.tv_sec = 1; // seconds timeout.tv_usec = 0; // micro seconds ( 0.5 seconds) setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(struct timeval)); // binding socket to a port rv = bind(sockfd, (struct sockaddr *) &client_address, sizeof(client_address)); if (rv < 0) { printf("MAIN: ERROR bind() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("socket is bound\n"); printf("MAIN: %li \n", client_address.sin_addr.s_addr); // connecting rv = connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)); info.server_address = server_address; info.client_address = client_address; info.sock_fd = sockfd; info.max_fd = sockfd; printf("rv = %i\n", rv); if (rv < 0) { printf("MAIN: ERROR connect() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("connected\n"); fd_set readset; FD_ZERO(&readset); FD_ZERO(&info.read_set); FD_SET(info.sock_fd, &info.read_set); while(1) { readset = info.read_set; printf("MAIN: %i \n", readset); ready = select((info.max_fd)+1, &readset, NULL, NULL, &timeout); if(ready == -1) { sleep(2); printf("TEST: MAIN: ready = -1. %s \n", strerror(errno)); } else if (ready == 0) { sleep(2); printf("TEST: MAIN: ready = 0. %s \n", strerror(errno)); } else if (ready > 0) { printf("TEST: MAIN: ready = %i. %s at socket %i \n", ready, strerror(errno), i); for(i = 0; i < ((info.max_fd)+1); i++) { if(FD_ISSET(i, &readset)) { rv = recv(sockfd, &msg, 500, 0); if(rv < 0) continue; else if(rv > 0) printf("MAIN: TEST: %s %s \n", msg._command[0], msg._payload); else if (rv == 0) { sleep(3); printf("MAIN: TEST: SOCKET CLOSEDDDDDD \n"); } FD_CLR(i, &readset); } } } info.read_set = readset; } // close connection close(sockfd); printf("socket closed. BYE! \n"); return(0); }

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  • Using nested classes for constants?

    - by antirysm
    What's wrong with using nested classes to group constants? Like so: public static class Constants { public static class CategoryA { public const string ValueX = "CatA_X"; public const string ValueY = "CatA_Y"; } public static class CategoryB { public const string ValueX = "CatB_X"; public const string ValueY = "CatB_Y"; } } Used like so: Console.WriteLine(Constants.CategoryA.ValueY); Console.WriteLine(Constants.CategoryB.ValueX); You could also make the "Constants"-class partial...

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  • Any way in C++ to forward declare a function prototype?

    - by jsyjr
    I make regular use of forward class declarations and pointers to such classes. I now have a need to pass a function pointer through a number of layers. I would prefer to include the header that declares my function pointer's prototype only into the module that dereferences a function pointer rather than into each layer that simply passes along that pointer value. Is this possible?

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  • C Array of string

    - by Meko
    HI. This is maybe simple question but I want to create two dimensional array and add it string like in java string str = "text" ; string [][] array = new [][] string ; array[i][j] = str ; But in C there is no string .I tried like this but here strcpy() gives error.It returns to assembly code. I am trying to read line by line from text and split line by space and add them to structure.But first I think that I must add each line and row in array and then making iteration and adding to structures fields. static const char filename[] = "student.txt"; FILE *file = fopen ( filename, "r" ); char line [ 128 ]; /* or other suitable maximum line size */ char delims [ ]=" "; char *result =NULL; char list[15]; char arra[128][128]; int i=0; int j=0; struct { char gruppa[10]; char familiya[20]; int uchaste; struct { int firsth; int second; int third; int fourht; int fifth; } exam; }student; for(i=0; i<128; i++) for(j=0; j<128; j++) arra[i][j] = '\0'; for(i=0; i<15; i++) list[i] = '\0'; if ( file != NULL ) { while ( fgets ( line, sizeof line, file ) != NULL ) { result = strtok(line,delims); while (result !=NULL) { strcpy(list,("%s",result)); strcpy(arra[i][j],list); // Here it gives errror j++; result = strtok(NULL,delims); } j=0; i++; } fclose ( file ); } else { perror ( filename ); } getchar(); return 0; }

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  • Use jQuery to alter css for "html" and "*"

    - by Chris
    Apologies if this is incredibly easy but I want to be able to do the following in jQuery. Current CSS * { cursor: url('/web/resources/graphics/blank.cur'), pointer; } html { cursor: url('/web/resources/graphics/blank.cur'), pointer; } Desired CSS change (through jQuery only) * { cursor: url('/web/resources/graphics/blankDot.cur'), pointer; } html { cursor: url('/web/resources/graphics/blankDot.cur'), pointer; }

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  • replacing a path with sed

    - by compie
    How can I use sed to replace this line char * path_list_[1] = { "/some/random/path" }; with this line char * path_list_[2] = { "lib/foo", "lib/bar" }; in a file named source.c Notes: * The path is really random. * Your solution should only change this line in source.c * I'm only interested in a sed oneliner. You can use this Python regex as a starting point: text = re.sub('static const char \* path_list_\[1\] = \{ "[^"]*" \};', 'static const char * path_list_[2] = { "lib/sun", "lib/matlab" };', text)

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