View Compilation Error

0_0_18413172_11989.cpp: In function 'int cmp1(stu, stu)':
0_0_18413172_11989.cpp:13:29: error: 'strcmp' was not declared in this scope
  return strcmp(a.node,b.node)<0;
                             ^
0_0_18413172_11989.cpp: In function 'int cmp2(stu, stu)':
0_0_18413172_11989.cpp:17:26: error: 'strcmp' was not declared in this scope
  if(!strcmp(a.name,b.name))
                          ^
0_0_18413172_11989.cpp: In function 'int cmp3(stu, stu)':
0_0_18413172_11989.cpp:24:29: error: 'strcmp' was not declared in this scope
  return strcmp(a.node,b.node)<0;
                             ^