View Compilation Error

0_0_28746333_9498.c: In function 'check':
0_0_28746333_9498.c:14:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i=0;i<len;i++) {
     ^
0_0_28746333_9498.c:14:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_28746333_9498.c: In function 'main':
0_0_28746333_9498.c:33:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=1;i<len;i++){
         ^