View Compilation Error

0_0_33279043_7720.c: In function 'main':
0_0_33279043_7720.c:8:13: error: 'f' undeclared (first use in this function)
             f[1] = 2;
             ^
0_0_33279043_7720.c:8:13: note: each undeclared identifier is reported only once for each function it appears in
0_0_33279043_7720.c:9:13: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
             for(int i=2;i<n;i++){
             ^
0_0_33279043_7720.c:9:13: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code