In C language, I want to access a global static variable outside the scope of the file . Let me know the best possible way to do it. One of the methods is to assign an extern global variable the value of static variable, In file a.c static int val=10; globalvar =val; In file b.c extern globalvar ; But in this case any changes in val...
I am having some trouble with IEEE floating point rules preventing compiler optimizations that seem obvious. For example, char foo(float x) { if (x == x) return 1; else return 0; } cannot be optimized to just return 1 because NaN == NaN is false. Okay, fine, I guess. However, I want to write such that the ...
I want to create a thread in C so that the thread automatically call after two seconds. I am using Visual Studio and Windows platform for development. How do I get started? ...
I generally use dbx for debugging C code. How do we log the complete session of the dbx from the point I started to the point I fired the quit command in dbx? ...
I have used this type of convention many times in my code in the past: strcpy ( cTmpA, "hello" ); sprintf ( cTmpA, "%s world", cTmpA ); Recently I switched my legacy C compiler to Visual Studio 2005, and found I got a garbled string resulting from the above code. It then occurred to me that perhaps the behaviour of sprintf() is not ri...
Hi I am writtnig a simply Client - Server program. In this program I have to use getopt() library to get port number and ip address like this: server -i 127.0.0.1 -p 10001 I do not know how can i get a values form optarg, to use they later in program. And ofcourse sorry for my english. This is not my native language. :) ...
I have the following code in C. void setNonBlocking(SOCKET fd){ int flags; if (-1 == (flags = fcntl(fd, F_GETFL, 0))) flags = 0; fcntl(fd, F_SETFL, flags | O_NONBLOCK); } int main(){ int sock; connect(sock, .....); setNonBlocking(sock); .... close(sock); //we will do something here but the application exits in/af...
I have C++ objects and I have Lua objects/tables. (Also have SWIG C++ bindings.) What I need to be able to do is associate the two objects so that if I do say CObject* o1 = getObject(); o1->Update(); it will do the equivalent Lua: myluatable1.Update(); So far I can imagine that CObject::Update would have the following code: void ...
I am trying to test some typical cuda functions during the configure process. How can I write it in my configure.ac? Something like: AC_TRY_COMPILE([], [ __global__ static void test_cuda() { const int tid = threadIdx.x; const int bid = blockIdx.x; __syncthreads(); } ], [cuda_comp=ok],[cuda_comp=no]) But nvcc is not defined...
I'm learning C through The C Programming Language 2nd Edition and it refers to symbolic constants where you use #define before main() to assign a label to a value. For instance this is the program I am trying to use - > #include <stdio.h> #define LOWER 0 #define UPPER 300 #define STEP 20 main() { int fahr; for (fahr = LOWER; ...
I am migrating a LynxOS program to an ubuntu distribution and gcc 4.1.3 I am almost done but I have a problem, I am receiving SIGALRM signal which forces my program to exit. I dont know why I am receiving this signals if I am not calling to alarm(x). I roundabouted this with a sigaction, but my program is not working properly mq_receiv...
What's this easiest / most efficient way to initialize these blocks of doubles, preferably at compile time: #define N 1000 double mul1[N][N] __attribute__ ((aligned (64))); double mul2[N][N] __attribute__ ((aligned (64))); They're used for "const" read only test data. ...
Hi all.. In C, i have read tat half-initialized arrays will be filled with zeros for the rest of the elements (irrespective of integer or char arrays).. Eg: int arr[10] = {3}; arr[4] will be 0 if initialized and a junk value if not initialized My question is, will the above work for all C compilers (or) this appending of zeros mi...
I'm trying to combine words from characters which i'm reading from a file. The problem is in the combining the characters. The way I'm doing it is the following: char *charArr while( (readChar = fgetc(fp)) != EOF ){ charArr[i] = readChar; i++; } ...
why isn't the size of an array sent as a parameter the same as within main? #include <stdio.h> void PrintSize(int p_someArray[10]); int main () { int myArray[10]; printf("%d\n", sizeof(myArray)); /* as expected 40 */ PrintSize(myArray);/* prints 4 not 40 */ } void PrintSize(int p_someArray[10]){ printf("%d\n", sizeof(...
Hi Everyone, I am writing a program to try to solve a math problem. I need to generate a unique list of all of the numbers that add up to another number. For example, all of the unqiue combinations of 4 numbers that add up to 5 are: 5 0 0 0 4 1 0 0 3 2 0 0 3 1 1 0 2 2 1 0 2 1 1 1 This is easy to brute force in perl but I am workin...
I'm trying to modify this code in an attempt to make it work on an Arduino Mega. I'm pretty much new to C, so I may have made some major mistakes. By the way, this is for a self balancing skateboard. This code is taken from an ATmega32 (from here) and I'm trying to make it work on a Arduino Mega. This code was written for an ATmega32 ...
I've recently enabled -pedantic option on gcc and now I've got about two or three pages of "ISO C90 forbids mixed declaration and code" warnings. My goal with this project is to be able to deploy it on any mainstream system with a c compiler, so I realize it wouldn't be wise to assume that C99 will be supported everywhere, but is it eve...
Okay, I've seen many posts here about odd idioms and common practices in C that might not be initially intuitive. Perhaps a few examples are in order Elements in an array: #define ELEMENTS(x) (sizeof (x) / sizeof (*(x))) Odd array indexing: a[5] = 5[a] Single line if/else/while/for safe #defines #define FOO(X) do { f(X); g(X); } ...
Hi All, Are there any guidelines available that can be followed before calling standard string operation related functions in C? For example, how much optimization will comparing the first character of two strings (and checking if they are equal) before calling strcmp provide? What types of overhead related to string related functions...