I got trouble making functions in c++

[OlaveraLuffy]

Help from my code?

  // Calculator.cpp - This program performs arithmetic, ( +. -, *. / ) on two numbers.
// Input:  Interactive
// Output:  Result of arithmetic operation

#include <iostream>
#include <string>
using namespace std;

// Write performOperation() function declaration here

int main() 
{
   double numberOne, numberTwo;              	
   string operation;
   double result; 	
						
   cout << "Enter the first number: ";
   cin >> numberOne; 
   cout << "Enter the second number: ";
   cin >> numberTwo; 
   cout << "Enter an operator (+.-.*,/): ";
   cin >> operation;
		
   // Call performOperation method here		
   

   cout << numberOne;
   cout << " " << operation << " ";
   cout << numberTwo;
   cout << " = ";
   cout << result << endl;
	
   return 0;

} // End of main() function
	
	
// Write performOperation function here 

[kbw]

You can call it like this:

#include <iostream>
#include <string>
using namespace std;

double performOperation(string operation, double numberOne, double numberTwo)
{
    // you need to provide the implementation here.
    return 0.0;
}

int main() 
{
   double numberOne, numberTwo;              	
   string operation;
   double result; 	
						
   cout << "Enter the first number: ";
   cin >> numberOne; 
   cout << "Enter the second number: ";
   cin >> numberTwo; 
   cout << "Enter an operator (+.-.*,/): ";
   cin >> operation;

   result = performOperation(operation, numberOne, numberTwo);

   cout << numberOne;
   cout << " " << operation << " ";
   cout << numberTwo;
   cout << " = ";
   cout << result << endl;
	
   return 0;
}

[E0p9LyTq]

Why use a std::string when your operator input is a single character?

Passing Plain Old Data variables "by value" as parameters by copying them is a trivial expense, but passing them as pointers or references is a better technique to learn for later when dealing with classes and structs that can be quite a chore to copy.

If you pass by pointer or reference then making the parameters const is recommended if you don't want to change the parameters in the function.

#include <iostream>

double performOperation(const char&, const double&, const double&);

int main()
{
   std::cout << "Enter the first number: ";
   double numberOne;
   std::cin >> numberOne;

   std::cout << "Enter the second number: ";
   double numberTwo;
   std::cin >> numberTwo;
   std::cout << "Enter an operator (+, -, *, /): ";
   char operation;
   std::cin >> operation;

   double result = (operation, numberOne, numberTwo);

   std::cout << numberOne << " " << operation << " " << numberTwo << " = " << result << '\n';

   return 0;
}

double performOperation(const char& operation, const double& numberOne, const double& numberTwo)
{
   // do the math op magic here.

   return 0.0;
}