View Compilation Error

0_0_16275162_9984.c: In function 'main':
0_0_16275162_9984.c:10:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for (int i = 0; i < strlen(c); i += 2)
   ^
0_0_16275162_9984.c:10:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code