View Compilation Error

0_0_35247045_23148.c: In function 'main':
0_0_35247045_23148.c:12:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=0; arr[i]; i++)
         ^
0_0_35247045_23148.c:12:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_35247045_23148.c:21:17: error: redefinition of 'i'
         for(int i=1; i<=n; i++)
                 ^
0_0_35247045_23148.c:12:17: note: previous definition of 'i' was here
         for(int i=0; arr[i]; i++)
                 ^
0_0_35247045_23148.c:21:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=1; i<=n; i++)
         ^