View Compilation Error

0_0_20738364_18972.c: In function 'main':
0_0_20738364_18972.c:20:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i = 0; i<n; i++)
         ^
0_0_20738364_18972.c:20:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_20738364_18972.c:24:13: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
             for(int j = 0; j<l; j++)
             ^
0_0_20738364_18972.c:33:3: error: expected expression before '/' token
   //int len=strlen(b);
   ^
0_0_20738364_18972.c:35:11: error: redefinition of 'i'
   for(int i=0;i<len;i++)
           ^
0_0_20738364_18972.c:20:17: note: previous definition of 'i' was here
         for(int i = 0; i<n; i++)
                 ^
0_0_20738364_18972.c:35:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int i=0;i<len;i++)
   ^