int main() { int a = 12; } $ gcc maintest.c $ ./a.out $ echo $? 148
$ cat test.c int main(void) {int a = 12;} $ gcc-6 test.c -o test --std=c89; ./test; echo $? 162 $ gcc-6 test.c -o test --std=c99; ./test; echo $? 0
