c99

Is there a hack to support range case in a c(99?) or objective C switch statement ? I know this is not supported to write something like this: switch(x) case 1: case 2..10: case 11: But I was thinking there should be a way to generate code with a #define macro. Of course I can define a macro with the list of cases but I was hoping for a more elegant way like CASERANGE(x,x+10) which would generate: case x case x+1 case x+2 is it even possible ? GCC has an extension to the C language that allows something similar to your first example, but other than that, if there was a portable/ANSI way of

I've looked at SO/IEC 9899:201x under J.1 Unspecified behavior: "The order in which subexpressions are evaluated and the order in which side effects take place, except as specified for the function-call (), &&, ||, ?:, and comma operators (6.5)." Does this means that in func1() + func2(); func2() may be preformed before func1(), or even during func1() ? In the current standard (ISO/IEC 9899:1999) there is a sequence point between function calls but the order of evaluation of the operands to + is not specified so func1 may be called before or after func2 but the function calls must not overlap

I've tried to compile a code using a bool variable in C and I've included the stdbool header but when I compiled it I didn't specify that I want to compile it with the c99 standard (so it was compiled with ANSI C standard) but it worked anyway. I was wondering why is that ? Here's the code : #include <stdio.h> #include <stdbool.h> int main() { char name[20]; printf("What's your name ? "); gets(name); printf("Nice to meet you %s.\n", name); bool exit = false; char c; printf("Do you wish to exit the program ? (Y/N) "); while (!exit) { c = getchar(); if (c == '\n') { continue; } printf("Do you

Suppose I have a global variable that contains a large structure: typedef struct { char Big[1024] } LARGE; static LARGE x; void main() { free(x); } Can I safely call free(x) from main when I dont need it anymore? No. You didn't dynamically allocate x so don't need to (and cannot) free it. If you absolutely need to free the memory before your program exits, declare a pointer as global, allocate it on demand, using malloc or calloc , then free it when you're finished with the structure. static LARGE* x; void main() { x = malloc(sizeof(*x)); // use x free(x); } No, free can only be used to

I'm having an issue compiling code - specifically METIS - Serial Graph Partitioning and Fill-reducing Matrix Ordering . I've successfully managed to make Visual Studio 2013 Project out of the source files two ways: using CMake GUI (version 3.4.3) and using Command Line. However, in both cases when I try to build the created project in Visual Studio, I'm getting an error: Error C2059: syntax error : '(' on line _CRTIMP double __cdecl rint(_In_ double _X); where _CRTIMP is defined this way: #define _CRTIMP __declspec(dllimport) Is this issue caused in the process of creating Visual Studio

Are Statement and Declarations in Expressions specific to GNU C ? Or this feature is also included in C99 standard ? It's a GCC extension. (See the GCC docs, e.g. here for gcc 4.3.3 , for a full list of GCC extensions; and the C99 spec is available here .) GCC will warn about such things if you use the -pedantic -std=c99 flags, e.g.: $ cat foo.c int main(void) { return ({ int a = 0; a; }); } $ gcc -pedantic -std=c99 -c foo.c foo.c: In function 'main': foo.c:3: warning: ISO C forbids braced-groups within expressions While this is not a C99 standard, this extension is not specific to gcc either.

I am experimenting with the use of Variable Length Arrays (VLAs) in my C code and trying to iron out my understanding of what they should and shouldn't do. I have the following snippet from my function: void get_pdw_frame_usb(pdws_t *pdw_frame, pdw_io_t *pdw_io) { ... unsigned char buf[pdw_io->packet_size]; unsigned char *pdw_buf; memset(buf, '\0', sizeof(buf)); pdw_io is a data structure containing, amongst other things, packet_size , which is of type size_t the char array buf is to be used to store the contents of a usb bulk transfer packet I'm trying to instantiate it here as an automatic

I am puzzled. I have no explanation to why this test passes when using the double data type but fails when using the float data type. Consider the following snippet of code. float total = 0.00; for ( int i = 0; i < 100; i++ ) total += 0.01; One would anticipate total to be 1.00, however it is equal to 0.99. Why is this the case? I compiled with both GCC and clang, both compilers have the same result. The value for 0.01 in decimal is expressed as the series: a1*(1/2) + a2*(1/2)^2 + a3*(1/2)^4 + etc. where aN is a zero or one. I leave it to you to figure out the specific values of a1, a2 and how