View Compilation Error

0_0_21784270_18603.c: In function 'v2':
0_0_21784270_18603.c:39:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int i = 1; i < 6; ++i) r += magic[i] * expdu(l, i);
  ^
0_0_21784270_18603.c:39:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_21784270_18603.c: In function 'check':
0_0_21784270_18603.c:62:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(size_t i = 0; i < n; ++i){
  ^
0_0_21784270_18603.c: In function 'solve':
0_0_21784270_18603.c:80:1: error: expected expression before '/' token
 //  if(absd(v - h) < 1e-13) break;
 ^
0_0_21784270_18603.c: In function 'main':
0_0_21784270_18603.c:89:2: error: expected expression before '/' token
  //check(v1, v2, 0, 1e-6, 500000);
  ^