View Compilation Error

0_0_16854789_20584.c: In function 'compare':
0_0_16854789_20584.c:4:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int i=num-1; i>0; i--)
  ^
0_0_16854789_20584.c:4:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_16854789_20584.c:5:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int j=0; j<i; j++)
   ^
0_0_16854789_20584.c: In function 'main':
0_0_16854789_20584.c:19:1: error: expected declaration or statement at end of input
 return 0;
 ^