View Compilation Error

0_0_17617022_13392.cpp: In function 'bool cmp1(node, node)':
0_0_17617022_13392.cpp:11:23: error: 'strcmp' was not declared in this scope
  return strcmp(a.s,b.s)<0?true:false;
                       ^
0_0_17617022_13392.cpp: In function 'bool cmp2(node, node)':
0_0_17617022_13392.cpp:15:25: error: 'strcmp' was not declared in this scope
  if(strcmp(a.name,b.name)==0)
                         ^
0_0_17617022_13392.cpp:17:29: error: 'strcmp' was not declared in this scope
  return strcmp(a.name,b.name)<0?true:false;
                             ^
0_0_17617022_13392.cpp: In function 'bool cmp3(node, node)':
0_0_17617022_13392.cpp:22:24: error: 'strcmp' was not declared in this scope
   return strcmp(a.s,b.s)<0?true:false;
                        ^