if statement - chained if-else not working (C++) -

i'm beginner , having trouble chained if-else statement. when run program, , enter item select, outputs "invalid entry.". why isn't executing proper function when equal in if-statement?

thank you,

don

#include <iostream> using namespace std;  int sum(int int1, int int2 ){      return int1 + int2;  }  int difference( int int1, int int2 ){      return int1 - int2;  }  int product( int int1, int int2 ){      return int1 * int2;  }  int quotient( int int1, int int2 ){      return int1 / int2;  }  int main(){  cout << "\nwelcome calculator.\n\n"; cout << "please enter 2 numbers.\n\n";  int a; int b; cin >> >> b;  cout << "what these numbers?\nhere options: add, subtract, multiply, or divide.\n\n";  string add; string subtract; string multiply; string divide;  string choice; cin >> choice;   if( choice == add )     cout << sum( a, b ); else if ( choice == subtract )     cout << difference( a, b ); else if ( choice == multiply )     cout << product( a, b ); else if ( choice == divide )     cout << quotient( a, b ); else      cout << "invalid entry.\n";   return 0;  } 

with statement:

string add; 

you creating string variable name add, there not yet value assigned it. when compare variable user input, program see add value null , not equal whatever user inputs.

you want assign value it:

string add = "add"; 

and other strings same.

and compare std::string:

if(choice == add) 

another way it, check directly constant string:

if(choice == "add"){   //do }else if(choice == "subtract")    //do else