View Compilation Error

0_0_20189240_18551.c: In function 'main':
0_0_20189240_18551.c:8:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int t = 0; t < T; ++t)
  ^
0_0_20189240_18551.c:8:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_20189240_18551.c:14:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int n1 = 0; n1 < num; ++n1)
   ^
0_0_20189240_18551.c:25:11: error: redefinition of 'n1'
   for(int n1 = 0; n1 < count; ++n1)
           ^
0_0_20189240_18551.c:14:11: note: previous definition of 'n1' was here
   for(int n1 = 0; n1 < num; ++n1)
           ^
0_0_20189240_18551.c:25:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int n1 = 0; n1 < count; ++n1)
   ^
0_0_20189240_18551.c:27:4: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
    for(int n2 = n1 + 1; n2 < count; ++n2)
    ^