View Compilation Error

0_0_33157142_11958.cpp: In function 'int cmp1(node, node)':
0_0_33157142_11958.cpp:13:29: error: 'strcmp' was not declared in this scope
  return strcmp(aa.num,bb.num)<0;
                             ^
0_0_33157142_11958.cpp: In function 'int cmp2(node, node)':
0_0_33157142_11958.cpp:17:27: error: 'strcmp' was not declared in this scope
  if(strcmp(aa.name,bb.name)!=0)
                           ^
0_0_33157142_11958.cpp: In function 'int cmp3(node, node)':
0_0_33157142_11958.cpp:25:30: error: 'strcmp' was not declared in this scope
   return strcmp(aa.num,bb.num)<0;
                              ^