View Compilation Error

0_0_18713073_30760.cpp: In function 'int main()':
0_0_18713073_30760.cpp:45:35: error: '_sell' was not declared in this scope
          else if(s[0]=='S') _sell();
                                   ^
0_0_18713073_30760.cpp:46:37: error: '_cancle' was not declared in this scope
          else if(s[0]=='C') _cancle();
                                     ^
0_0_18713073_30760.cpp:47:37: error: '_modify' was not declared in this scope
          else if(s[0]=='M') _modify();
                                     ^
0_0_18713073_30760.cpp:49:21: error: '_printf' was not declared in this scope
             _printf();
                     ^