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  • How to specify blob type in MS Access?

    - by Firat
    How to specify blob type in MS Access? I have office 2007 installed. I am using jdbc, but this should not matter for the SQL query I am passing. Tried to pass a length to it, or FILE type, did not help. CREATE TABLE mytable ( [integer] INTEGER not null, [string] VARCHAR (255), [datetime] DATETIME, [boolean] BIT, [char] CHAR, [short] SHORT, [double] DOUBLE, [float] FLOAT, [long] LONG, [blob] BLOB, // does not work Primary Key ([integer]) )

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  • compilation error in vc++ vs2005

    - by vijay.j
    I am getting an error while compiling in vc++ vs2005. error LNK2019: unresolved external symbol __imp__MessageBoxA@16 referenced in function "void __cdecl MsgBox(char const *,char const *,...)" (?MsgBox@@YAXPBD0ZZ)

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  • async_write/async_read problems while trying to implement question-answer logic

    - by Max
    Good day. I'm trying to implement a question - answer logic using boost::asio. On the Client I have: void Send_Message() { .... boost::asio::async_write(server_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent.\n"; .... boost::asio::async_read(server_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... } And on the Server i have the "same - logic" code: void Read_Message() { .... boost::asio::async_read(client_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... boost::asio::async_write(client_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent back.\n"; .... } Message it's just a structure. And the output on the Client is: Message was sent. Output on the Server is: I have a new message. And that's all. After this both programs are still working but nothing happens. I tried to implement code like: if (!error) { .... } else { // close sockets and etc. } But there are no errors in reading or writing. Both programs are just running normally, but doesn't interact with each other. This code is quite obvious but i can't understand why it's not working. Thanks in advance for any advice.

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  • Simple RSA encryption (Java)

    - by jake blue
    This is simply for fun. This will not be used for any actual encryption. I'm only first year comp sci student and love cryptography. This took a long time to get working. At approximately N = 18, it begins breaking down. It won't encrypt messages properly after that point. I'm not sure why. Any insights? I'd also appreciate any links you could provide me to tutorials or interesting reading about Cryptography. import java.math.BigInteger; import java.security.SecureRandom; /** * Cryptography. * * Generates public and private keys used in encryption and * decryption * */ public class RSA { private final static BigInteger one = new BigInteger("1"); private final static SecureRandom random = new SecureRandom(); // prime numbers private BigInteger p; private BigInteger q; // modulus private BigInteger n; // totient private BigInteger t; // public key private BigInteger e; // private key private BigInteger d; private String cipherText; /** * Constructor for objects of class RSA */ public RSA(int N) { p = BigInteger.probablePrime(N/2, random); q = BigInteger.probablePrime(N/2, random); // initialising modulus n = p.multiply(q); // initialising t by euclid's totient function (p-1)(q-1) t = (p.subtract(one)).multiply(q.subtract(one)); // initialising public key ~ 65537 is common public key e = new BigInteger("65537"); } public int generatePrivateKey() { d = e.modInverse(t); return d.intValue(); } public String encrypt(String plainText) { String encrypted = ""; int j = 0; for(int i = 0; i < plainText.length(); i++){ char m = plainText.charAt(i); BigInteger bi1 = BigInteger.valueOf(m); BigInteger bi2 = bi1.modPow(e, n); j = bi2.intValue(); m = (char) j; encrypted += m; } cipherText = encrypted; return encrypted; } public String decrypt() { String decrypted = ""; int j = 0; for(int i = 0; i < cipherText.length(); i++){ char c = cipherText.charAt(i); BigInteger bi1 = BigInteger.valueOf(c); BigInteger bi2 = bi1.modPow(d, n); j = bi2.intValue(); c = (char) j; decrypted += c; } return decrypted; } }

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  • Function overloading in C

    - by Andrei Ciobanu
    Today, looking at the man page for open(), I've noticed this function is 'overloaded': int open(const char *pathname, int flags); int open(const char *pathname, int flags, mode_t mode); I didn't thought it's possible on C. What's the 'trick' for achieving this ?

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  • g++ compiler complains about conversions between related types (from int to enum, from void* to clas

    - by Slav
    g++ compiler complains about conversions between related types (from int to enum, from void* to class*, from const char* to unsigned char*, etc.). Compiler handles such convertions as errors and won't compile furthermore. It occurs only when I compile using Dev-C++ IDE, but when I compile the same code (using the compiler which Dev-C++ uses) such errors (even warnings) do not appears. How to mute errors of such types?

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  • Change an array's value in x86 assembly (embedded in C++)

    - by VV
    I am messing around with assembly for the first time, and can't seem to change the index values of an array. Here's the method I am working on int ascending_sort( char arrayOfLetters[], int arraySize ) { char temp; __asm { //??? } } And these are what I tried mov temp, 'X' mov al, temp mov arrayOfLetters[0], al And this gave me an error C2415: improper operand type so I tried mov temp, 'X' mov al, temp mov BYTE PTR arrayOfLetters[0], al This complied, but it didn't change the array...

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  • Must parameter of assignment operator be reference?

    - by Tim
    When overloading assignment operator of a class in C++, must its parameter be reference? For example, class MyClass { public: ... MyClass & operator=(const MyClass &rhs); ... } Can it be class MyClass { public: ... MyClass & operator=(const MyClass rhs); ... } ? Thanks!

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  • C++ Beginner - 'friend' functions and << operator overloading: What is the proper way to overload an

    - by Francisco P.
    Hello, everyone! In a project I'm working on, I have a Score class, defined below in score.h. I am trying to overload it so, when a << operation is performed on it, _points + " " + _name is returned. Here's what I tried to do: ostream & Score::operator<< (ostream & os, Score right) { os << right.getPoints() << " " << right.scoreGetName(); return os; } Here are the errors returned: 1>c:\users\francisco\documents\feup\1a2s\prog\projecto3\projecto3\score.h(30) : error C2804: binary 'operator <<' has too many parameters (This error appears 4 times, actually) I managed to get it working by declaring the overload as a friend function: friend ostream & operator<< (ostream & os, Score right); And removing the Score:: from the function declaration in score.cpp (effectively not declaring it as a member). Why does this work, yet the code describe above doesn't? Thanks for your time! Below is the full score.h /////////////////////////////////////////////////////////// // Score.h // Implementation of the Class Score // Created on: 10-Mai-2010 11:43:56 // Original author: Francisco /////////////////////////////////////////////////////////// #ifndef SCORE_H_ #define SCORE_H_ #include <string> #include <iostream> #include <iostream> using std::string; using std::ostream; class Score { public: Score(string name); Score(); virtual ~Score(); void addPoints(int n); string scoreGetName() const; int getPoints() const; void scoreSetName(string name); bool operator>(const Score right) const; ostream & operator<< (ostream & os, Score right); private: string _name; int _points; }; #endif

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  • Method Overloading for NULL parameter

    - by Phani
    I have added three methods with parameters: public static void doSomething(Object obj) { System.out.println("Object called"); } public static void doSomething(char[] obj) { System.out.println("Array called"); } public static void doSomething(Integer obj) { System.out.println("Array called"); } When I am calling doSomething(null) , then compiler throws error as ambiguous methods. So Is the issue because Integer and char[] methods or Integer and Object methods?

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  • Unable to decode hex values in javascript tooltip

    - by staudk27
    Hi all, I have quite the process that we go through in order to display some e-mail communications in our application. Trying to keep it as general as possible... -We make a request to a service via XML -Get the XML reply string, send the string to a method to encode any invalid characters as follows: public static String convertUTF8(String value) { char[] chars = value.toCharArray(); StringBuffer retVal = new StringBuffer(chars.length); for (int i = 0; i < chars.length; i++) { char c = chars[i]; int chVal = (int)c; if (chVal > Byte.MAX_VALUE) { retVal.append("&#x").append(Integer.toHexString(chVal)).append(";"); } else { retVal.append(c); } } return retVal.toString(); } We then send that result of a string to another method to remove any other invalid characters: public static String removeInvalidCharacters(String inString) { if (inString == null){ return null; } StringBuffer newString = new StringBuffer(); char ch; char c[] = inString.toCharArray(); for (int i = 0; i < c.length; i++) { ch = c[i]; // remove any characters outside the valid UTF-8 range as well as all control characters // except tabs and new lines if ((ch < 0x00FD && ch > 0x001F) || ch == '\t' || ch == '\n' || ch == '\r') { newString.append(ch); } } return newString.toString(); } This string is then "unmarshal'ed" via the SaxParser The object is then sent back to our Display action which generated the response to the calling jsp/javascript to create the page. The issue is some text can contain characters which can't be processed correctly. The following is eventually rendered on the JSP just fine: <PrvwCommTxt>This is a new test. Have a*&amp;#xc7;&amp;#xb4;)&amp;#xa1;.&amp;#xf1;&amp;#xc7;&amp;#xa1;.&amp;#xf1;*&amp;#xc7;&amp;#xb4;)...</PrvwCommTxt> Which shows up as "This is a new test. Have a*Ç´)¡.ñÇ¡." in the browser. -The following shows up in a tooltip while hovering over the above text: <CommDetails>This is a new test. Have a*Ç´)¡.ñÇ¡.ñ*Ç´)¡.ñ*´)(¡.ñÇ(¡.ñÇ* Wonderful Day!</CommDetails> This then shows up incorrectly when rendered in the tooltip javascript with all the HEX values and not being rendered correctly. Any suggestions on how to make the unknown characters show correctly in javascript?

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  • Assigning values to chars in structs - c

    - by mrblippy
    Hi, i have been having trouble getting my head around allowing a user to enter words into structs. the struct i am using is below struct class { char class_num[4]; char *class_name } if anyone could point me how to do this or at least point me in the right direction that wuld be great. thanks

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  • How to create a simple Proxy to access web servers in C

    - by jesusiniesta
    Hi. I’m trying to create an small Web Proxy in C. First, I’m trying to get a webpage, sending a GET frame to the server. I don’t know what I have missed, but I am not receiving any response. I would really appreciate if you can help me to find what is missing in this code. int main (int argc, char** argv) { int cache_size, //size of the cache in KiB port, port_google = 80, dir, mySocket, socket_google; char google[] = "www.google.es", ip[16]; struct sockaddr_in socketAddr; char buffer[10000000]; if (GetParameters(argc,argv,&cache_size,&port) != 0) return -1; GetIP (google, ip); printf("ip2 = %s\n",ip); dir = inet_addr (ip); printf("ip3 = %i\n",dir); /* Creation of a socket with Google */ socket_google = conectClient (port_google, dir, &socketAddr); if (socket_google < 0) return -1; else printf("Socket created\n"); sprintf(buffer,"GET /index.html HTTP/1.1\r\n\r\n"); if (write(socket_google, (void*)buffer, LONGITUD_MSJ+1) < 0 ) return 1; else printf("GET frame sent\n"); strcpy(buffer,"\n"); read(socket_google, buffer, sizeof(buffer)); // strcpy(message,buffer); printf("%s\n", buffer); return 0; } And this is the code I use to create the socket. I think this part is OK, but I copy it just in case. int conectClient (int puerto, int direccion, struct sockaddr_in *socketAddr) { int mySocket; char error[1000]; if ( (mySocket = socket(AF_INET, SOCK_STREAM, 0)) == -1) { printf("Error when creating the socket\n"); return -2; } socketAddr->sin_family = AF_INET; socketAddr->sin_addr.s_addr = direccion; socketAddr->sin_port = htons(puerto); if (connect (mySocket, (struct sockaddr *)socketAddr,sizeof (*socketAddr)) == -1) { snprintf(error, sizeof(error), "Error in %s:%d\n", __FILE__, __LINE__); perror(error); printf("%s\n",error); printf ("-- Error when stablishing a connection\n"); return -1; } return mySocket; } Thanks!

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  • if string is alphabetically greater than other string in objective

    - by Jonathan
    I'm trying to use an if statement to work out which of 2 strings comes first alphabetically. Like with numbers and greater and less than: if (1 < 2) { just with strings: if(@"ahello" < @"bhello") { Or would I have to have a string containing all the letters and then check the index of the first char in each string and see which index is greater, and the index that is less than the other comes first in the alphabet and then if they are equal move on to the next char and repeat?

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  • c++ global operator not playing well with template class

    - by John
    ok, i found some similar posts on stackoverflow, but I couldn't find any that pertained to my exact situation and I was confused with some of the answers given. Ok, so here is my problem: I have a template matrix class as follows: template <typename T, size_t ROWS, size_t COLS> class Matrix { public: template<typename, size_t, size_t> friend class Matrix; Matrix( T init = T() ) : _matrix(ROWS, vector<T>(COLS, init)) { /*for( int i = 0; i < ROWS; i++ ) { _matrix[i] = new vector<T>( COLS, init ); }*/ } Matrix<T, ROWS, COLS> & operator+=( const T & value ) { for( vector<T>::size_type i = 0; i < this->_matrix.size(); i++ ) { for( vector<T>::size_type j = 0; j < this->_matrix[i].size(); j++ ) { this->_matrix[i][j] += value; } } return *this; } private: vector< vector<T> > _matrix; }; and I have the following global function template: template<typename T, size_t ROWS, size_t COLS> Matrix<T, ROWS, COLS> operator+( const Matrix<T, ROWS, COLS> & lhs, const Matrix<T, ROWS, COLS> & rhs ) { Matrix<T, ROWS, COLS> returnValue = lhs; return returnValue += lhs; } To me, this seems to be right. However, when I try to compile the code, I get the following error (thrown from the operator+ function): binary '+=' : no operator found which takes a right-hand operand of type 'const matrix::Matrix<T,ROWS,COLS>' (or there is no acceptable conversion) I can't figure out what to make of this. Any help if greatly appreciated!

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  • What the best approach to iterate and "store" files over a directory in C (Linux) ?

    - by Andrei Ciobanu
    I have written a function that checks if to files are duplicates or not. This function signature is: int check_dup_memmap(char *f1_name, char *f2_name) It returns: (-1) - If something went wrong; (0) - If the two files are similar; (+1) - If the two files are different; The next step is to write a function that iterates through all the files in a certain directory,apply the previous function, and gives a report on every existing duplicates. Initially I've thought to write a function that generates a file with all the filenames in a certain directory and then, read that file again and gain and compare every two files. Here is that version of the function, that gets all the filenames in a certain directory. void *build_dir_tree(char *dirname, FILE *f) { DIR *cdir = NULL; struct dirent *ent = NULL; struct stat buf; if(f == NULL){ fprintf(stderr, "NULL file submitted. [build_dir_tree].\n"); exit(-1); } if(dirname == NULL){ fprintf(stderr, "NULL dirname submitted. [build_dir_tree].\n"); exit(-1); } if((cdir = opendir(dirname)) == NULL){ char emsg[MFILE_LEN]; sprintf(emsg, "Cannot open dir: %s [build_dir_tree]\t",dirname); perror(emsg); } chdir(dirname); while ((ent = readdir(cdir)) != NULL) { lstat(ent->d_name, &buf); if (S_ISDIR(buf.st_mode)) { if (strcmp(".", ent->d_name) == 0 || strcmp("..", ent->d_name) == 0) { continue; } build_dir_tree(ent->d_name, f); } else{ fprintf(f, "/%s/%s\n",util_get_cwd(),ent->d_name); } } chdir(".."); closedir(cdir); } Still I consider this approach a little inefficient, as I have to parse the file again and again. In your opinion what are other approaches should I follow: Write a datastructure and hold the files instead of writing them in the file ? I think for a directory with a lot of files, the memory will become very fragmented. Hold all the filenames in auto-expanding array, so that I can easy access every file by their index, because they will in a contiguous memory location. Map this file in memory using mmap() ? But mmap may fail, as the file gets to big. Any opinions on this. I want to choose the most efficient path, and access as few resources as possible. This is the requirement of the program... EDIT: Is there a way to get the numbers of files in a certain directory, without iterating through it ?

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  • stxxl Assertion `it != root_node_.end()' failed

    - by Fabrizio Silvestri
    I am receiving this assertion failed error when trying to insert an element in a stxxl map. The entire assertion error is the following: resCache: /usr/include/stxxl/bits/containers/btree/btree.h:470: std::pair , bool stxxl::btree::btree::insert(const value_type&) [with KeyType = e_my_key, DataType = unsigned int, CompareType = comp_type, unsigned int RawNodeSize = 16384u, unsigned int RawLeafSize = 131072u, PDAllocStrategy = stxxl::SR, stxxl::btree::btree::value_type = std::pair]: Assertion `it != root_node_.end()' failed. Aborted Any idea? Edit: Here's the code fragment void request_handler::handle_request(my_key& query, reply& rep) { c_++; strip(query.content); std::cout << "Received query " << query.content << " by thread " << boost::this_thread::get_id() << ". It is number " << c_ << "\n"; strcpy(element.first.content, query.content); element.second = c_; testcache_.insert(element); STXXL_MSG("Records in map: " << testcache_.size()); } Edit2 here's more details (I omit constants, e.g. MAX_QUERY_LEN) struct comp_type : std::binary_function<my_key, my_key, bool> { bool operator () (const my_key & a, const my_key & b) const { return strncmp(a.content, b.content, MAX_QUERY_LEN) < 0; } static my_key max_value() { return max_key; } static my_key min_value() { return min_key; } }; typedef stxxl::map<my_key, my_data, comp_type> cacheType; cacheType testcache_; request_handler::request_handler() :testcache_(NODE_CACHE_SIZE, LEAF_CACHE_SIZE) { c_ = 0; memset(max_key.content, (std::numeric_limits<unsigned char>::max)(), MAX_QUERY_LEN); memset(min_key.content, (std::numeric_limits<unsigned char>::min)(), MAX_QUERY_LEN); testcache_.enable_prefetching(); STXXL_MSG("Records in map: " << testcache_.size()); }

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  • How to read and write a STL C++ string?

    - by cambr
    #include<string> ... string in; //How do I store a string from stdin to in? // //gets(in) - 16 cannot convert `std::string' to `char*' for argument `1' to //char* gets (char*)' // //scanf("%s",in) also gives some weird error Similarly, how do I write out in to stdout or to a file??

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  • Hide/Show some HTML table cells individually and align the remaining cells as they belong to the same row [closed]

    - by Brian
    [Edited at the resquest of admins] The best way I can explain my problem is showning an example. I have the table that you can see on the link below (since I can't post images...), that ha a table head (blue) and four rows, whose cells are green and white in color. I just want the white cells to hide/show alternately by clicking on green cells, which would remain always visible as parent cells. After hiding white cells, the green ones should be aligned into the same row, as they would fit like tetris bricks. That's all, I think more clear is impossible. http://i.stack.imgur.com/3n3In.jpg (follow the link to see the image explanation) The table code: <table class="columns" cellspacing="0" border="0"> <tr> <td class="left" rowspan="2"> <div style="text-align:center;"></div> </td> </tr><tr><td class="middle"> <div id="detail_table_source" style="display:none"></div> <br> <table id="detail_table" class="detail"> <colgroup> <col style="width:20px;"> <col style="width:40px;"> <col style="width:70px;"> <col style="width:20px;"> </colgroup> <thead> <tr> <th width="88">Blahhh</th> <th width="211">BLAHH</th> <th width="229">BLAHH</th> </tr> </thead> <tbody> <tr class="parent" id="row123" style="cursor: pointer; " title="Click to expand/collapse"> <td bgcolor="#A6A4CC">Blahhh</td> <td bgcolor="#A6A4CC">blah blah </td> <td bgcolor="#A6A4CC">Blahh</td> </tr> <tr class="child-row123" style="display: none; "> <td rowspan="3" bgcolor="#5B5B5B">&nbsp;</td> <td>blah blah </td> <td>blah blah</td> </tr> <tr class="child-row123" style="display: none; "> <td>blah blah</td> <td>blah blah</td> </tr> <tr class="child-row123" style="display: none; "> <td>blah blah</td> <td>blah blah</td> </tr> <tr> <td bgcolor="#6B7A94" class="parent" id="row456" style="cursor: pointer; " title="Click to expand/collapse"><strong>Blahh</strong></td> <td bgcolor="#FFFFFF" class="child-cell456" style="display: none; ">blah blah</td> <td bgcolor="#FFFFFF" class="child-cell456" style="display: none; ">blah blah</td> </tr> <tr> <td rowspan="4" valign="top" bgcolor="#5B5B5B" class="child-row456" style="display: none; ">&nbsp;</td> <td bgcolor="#6B7A94" class="parent" id="cell456" style="cursor: pointer; " title="Click to expand/collapse">blah blah</td> <td bgcolor="#6B7A94" class="parent" id="cell456" style="cursor: pointer; " title="Click to expand/collapse">blah blah</td> </tr> <tr> <td class="child-cell456" style="display: none; ">blah blah</td> <td class="child-cell456" style="display: none; ">blah blah</td> </tr> <tr> <td class="child-cell456" style="display: none; ">blah blah</td> <td class="child-cell456" style="display: none; ">blah blah</td> </tr> </tbody> </table> The script to hide/show whole rows (this works because it is copied from another example): <script language="javascript"> $(function() { $('tr.parent') .css("cursor","pointer") .attr("title","Click to expand/collapse") .click(function(){ $(this).siblings('.child-'+this.id).toggle(); }); $('tr[@class^=child-]').hide().children('td'); }); </script> And the failed attempt at expanding/hiding individual cells: <script language="javascript"> $(function() { $('td.parent') .css("cursor","pointer") .attr("title","Click to expand/collapse") .click(function(){ $(this).siblings('.child-'+this.id).toggle(); }); $('td[@class^=child-]').hide().children('td'); }); </script>

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  • Public Private Key Encryption Tutorials

    - by Jake M
    Do you know of a tutorial that demonstrates Public Private Key encryption(PPKE) in C++ or C? I am trying to learn how it works and eventually use Crypto++ to create my own encryptions using public private keys. Maybe theres a Crypto++ PPKE tutorial? Maybe someone can explain the relationship(if any) between the public and private keys? Could anyone suggest some very simple public and private key values I could use(like 'char*32','char/32') to create my simple PPKE program to understand the concept?

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  • C# Implicit array declaration

    - by The.Anti.9
    Basically, I want to be able to use string.Split(char[]) without actually defining a char array as a separate variable. I know in other languages you could do like string.split([' ', '\n']); or something like that. How would I do this in C#?

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