View Compilation Error

0_0_25978937_11840.c: In function 'main':
0_0_25978937_11840.c:9:1: error: expected expression before '/' token
 //    freopen("data.in", "r", stdin);
 ^
0_0_25978937_11840.c:10:1: error: expected expression before '/' token
 //    freopen("data.out", "w", stdout);
 ^