View Compilation Error

0_0_19103719_8005.c: In function 'main':
0_0_19103719_8005.c:8:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int i=0;i<n;i++){
   ^
0_0_19103719_8005.c:8:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_19103719_8005.c: In function 'avg':
0_0_19103719_8005.c:20:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int i=0;i<length;i++){
  ^
0_0_19103719_8005.c:27:10: error: redefinition of 'i'
  for(int i=0;i<length;i++){
          ^
0_0_19103719_8005.c:20:10: note: previous definition of 'i' was here
  for(int i=0;i<length;i++){
          ^
0_0_19103719_8005.c:27:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int i=0;i<length;i++){
  ^