View Compilation Error

0_0_20359880_18004.c: In function 'main':
0_0_20359880_18004.c:15:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int i=0;i<strlen(s);i++)
   ^
0_0_20359880_18004.c:15:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_20359880_18004.c:17:4: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
    for(int j=0;j<strlen(str);j++)
    ^