View Compilation Error

0_0_28658183_29535.c: In function 'main':
0_0_28658183_29535.c:12:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i = 1; i <= num; i++)
         ^
0_0_28658183_29535.c:12:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code