我怎么知道c的版本？

Question

The "\b" didn't work on my Mac. So I tried to find the reason.

I think that cause of this problem may be the version of C.

Or device could be. If you know it, can you help me? Thank you.

Answer 1

There are three ISO standard versions of C: C90, C99 and C11. To know which C version your program is running check the:

 __STDC_VERSION__

macro.

• For C90: the macro is undefined.
• For C99: the macro is defined with value 199901L.
• For C11: the macro is defined with value 201112L.

On the other hand if what you want to know is the version not of C but the version of your C compiler, as the other answers suggests, run the compiler with the appropriate option ( --version for both gcc and clang for example).

Depending on your compiler it can support different C versions. You can ask to change the compiler default C version used for compiling using the -std= option with gcc and clang , for example: -std=c90 , -std=c99 or -std=c11 .

Answer 2

int main() { if (__STDC_VERSION__ >= 201710L) printf("We are using C18!\n"); else if (__STDC_VERSION__ >= 201112L) printf("We are using C11!\n"); else if (__STDC_VERSION__ >= 199901L) printf("We are using C99!\n"); else printf("We are using C89/C90!\n"); return 0; }

Answer 3

based on what @chqrlie added...

#include <stdio.h>

int main() {
  #if defined __STDC_VERSION__ 
    long version = __STDC_VERSION__;
    if ( version == 199901 ) {
      printf ("version detected : C99\n");
    }
    if ( version == 201112 ) {
      printf ("version detected : C11\n");
    }
    if ( version == 201710 ) {
      printf ("version detected : C18\n");
    }
  #else 
    printf ("version detected : C90\n");
  #endif
}

Answer 4

Prerequisites : gcc should be installed.

You open your terminal and paste this bash command:

gcc -dM -E - < /dev/null | grep __STDC_VERSION__ | awk '{ print $2 " --> " $3 }'

For my case it returns __STDC_VERSION__ --> 201710L which translates to the 2017 C standard( c17 ). Yours can be c89 or c99 or c11

Answer 5

Slighly cleaner and bit more complete approach

#include <stdio.h>

int main(void) {

    #ifdef __STDC_VERSION__
        switch (__STDC_VERSION__) {
            case 199409:
                printf ("C version: C94 (%ld)", __STDC_VERSION__);
                break;
            case 199901:
                printf ("C version: C99 (%ld)", __STDC_VERSION__);
                break;
            case 201112:
                printf ("C version: C11 (%ld)", __STDC_VERSION__);
                break;
            case 201710:
                printf ("C version: C17 (%ld)", __STDC_VERSION__);
                break;
            default:
                printf ("C version: ?? (%ld)", __STDC_VERSION__);
                break;
        }
    #else
        printf ("C(89), C(90)");
    #endif

    #ifdef __STRICT_ANSI__
        printf (" (ANSI %d)\n", __STDC__);
    #else
        printf("\n");
    #endif


    return 0;
}

Test it with:

gcc main.c -o main -std=c90 && main
gcc main.c -o main -std=c99 && main
gcc main.c -o main -std=c11 && main
gcc main.c -o main -std=c17 && main

gcc main.c -o main -std=gnu89 && main
gcc main.c -o main -std=gnu99 && main
gcc main.c -o main -std=gnu11 && main
gcc main.c -o main -std=gnu17 && main

Answer 6

#include <stdio.h> 
//What version of C language you're using
int main() {
  if(__STDC_VERSION__ >=201710L)
    printf("The version is c18!\n");
  else if(__STDC_VERSION__ >= 201112L)
        printf("The version is C11! \n");
        else if (__STDC_VERSION__ >=199901L)
             printf("The version is C99!\n");
              else 
             printf("The version you're using is C89/C90");
 return 0;
  }