View Compilation Error

0_0_24602763_32698.cpp: In function 'bool cmp(node, node)':
0_0_24602763_32698.cpp:14:30: error: 'strcmp' was not declared in this scope
   return strcmp(a.time,b.time)<0;
                              ^
0_0_24602763_32698.cpp:16:30: error: 'strcmp' was not declared in this scope
   return strcmp(a.name,b.name)<0;
                              ^
0_0_24602763_32698.cpp: In function 'int main()':
0_0_24602763_32698.cpp:29:21: error: 'sort' was not declared in this scope
   sort(f+1,f+n+1,cmp);
                     ^
0_0_24602763_32698.cpp:34:35: error: 'strcmp' was not declared in this scope
    if(strcmp(f[i].time,f[i+1].time)==0)
                                   ^