View Compilation Error

0_0_31951573_5510.c: In function 'main':
0_0_31951573_5510.c:12:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int i = 0; a[i]; i++){
   ^
0_0_31951573_5510.c:12:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code