View Compilation Error

0_0_20231817_28164.c: In function 'main':
0_0_20231817_28164.c:11:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for (int i = 0, j = -1; i <= len; i++, j++) {
   ^
0_0_20231817_28164.c:11:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_20231817_28164.c:24:3: error: expected expression before '/' token
   //memset(str, 'a', sizeof(str) - 1);
   ^