Need Help on Simple calculator [Question

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Need Help on Simple calculator [Question

Need Help on Simple calculator [Question Answered]

Hello I am creating a simple calculator program using functions. The current problem that I am having is that I can't figure out a way to call the function to perform the calculation depending on what operator has been entered.

How would I make a display function to print out the equation and then the answer after the calculation function returns a value?

  #include<stdlib.h>
#include<cmath>
#include <iostream>

using namespace std;

// my prototypes

char menu ();
double getOperand ();
char getOperator ();
bool numOperandsNeeded (char);
double plus (double, char, double);
double sub (double, char, double);
double mult (double, char, double);
double div (double, char, double);
double rem (double, char, double);
double exp (double, char, double);
double log (double, char);
int factorial (int n);
double log (double, char);
void display2 (double, char, double);
void display1 (double, char);


int main ()
{
	double op1 =0;
	char optor = 0;
	double op2 =0;
	double ans =0;
   
    menu ();
	op1 = getOperand ();  
	optor = getOperator ();
	if((numOperandsNeeded (optor)) == 1)
	{ op2 = getOperand ();};
	
    /*switch (optor)
    {
           case '+':
                ans = plus(op1, op2);
           case '-':
                min ();
           case '*':
                mult ();
           case '/':
                div ();
           case '%':
                rem ();
           case '^':
                exp ();
           case 'L':
                log ();
           case '^':
                exp ();
           case '!':
                factorial ();
    }*/
    
	system ("pause");
	return EXIT_SUCCESS;
}

//functions
char menu()
{
  cout <<"Welcome to simple calculator!" << endl;
} 

double getOperand() 
{
  double op = 0;
  cout <<"Please enter a number"<< endl;
  cin >> op ;
  
  if (op >= 10000 || op <= -10000)
  {
    do 
  { 
    cout <<"Your Number is out of Range" ;
    cout << " Please Enter Another" << endl;
      
    cin >> op;
       

  }
    while (op >= 10000 || op <= -10000);
  
} 
 return op;
}

char getOperator ()
{
  char Optor = 0;
  cout << "Select an operator: " << endl;
  cout << " +, -, *, /, %, ^, !, L " << endl;
  cout << "Or 'q' to quit" << endl;
  cin >> Optor;
  
  while ( Optor == 'q')
  {
     return 0; 
  }
   
  if ( Optor == '+' || Optor == '-' || Optor == '*' || Optor == '/' || Optor == '%' || Optor == '^' || Optor == '!' || Optor == 'L')
  {
    return Optor;
  }
  else
  { 
    do 
    {
      cout << "The operator is not valid, please select another. " << endl;
      cin >> Optor; break;
    } while (Optor != '+' || Optor != '-' || Optor != '*' || Optor != '/' || Optor != '%' || Optor != '^' || Optor != '!' || Optor != 'L');
    
  }
  return Optor;
}

bool numOperandsNeeded (char Optor)
{
	switch (Optor)
    {
    	case '+':;
    	case '-':;
    	case '*':;
    	case '/':;
    	case '%':;
    	case '^': Optor = 1; break;
    
    	case '!':;
    	case 'L': Optor = 0; break;
    }
    return Optor;
}

double plus (double Op, char Optor, double Op2)
{
	double ans = 0;
	ans = Op + Op2;
	return ans;
}

double sub (double Op, char Optor, double Op2)
{
	double ans = 0;
	ans = Op - Op2;
	return ans;	
}

double mult (double Op, char Optor, double Op2)
{
	double ans = 0;
	ans = Op * Op2;
	return ans;	
}

double div (double Op, char Optor, double Op2)
{
	double ans = 0;
	ans = Op / Op2;
	return ans;
}

int rem (int Op, char Optor, int Op2)
{
	int ans = 0;
	ans = Op % Op2;
	return ans;
}

double exp (double Op, char Optor, double Op2)
{
	double ans = 0;
	ans = pow( Op, Op2);
	return ans;
}


int factorial(int Op) 
{ int i=0,fact=1; 
if (Op<=1) 
	{
	return(1); 
	} 
else 
	{
		for(i=1;i<=Op;i++) 
		{ 
			fact=fact*i; 
		} 
		return(fact); 
	}
}

double log (double Op, char Optor)
{
    
    double ans = 0;
		
	ans =(log (Op) / log (10));
	return ans;
}

Last edited on

closed account (o3hC5Di1)

Hi there,

You have a commented out switch-statement here that should do the trick with some minor alterations:

switch (optor)
    {
           case '+':
                ans = plus(op1, op2);
                break;
           case '-':
                min (op1,op2);
                break;
           case '*':
                mult (); //add arguments here
                break;
           case '/':
                div (); //add arguments here
                break;
           case '%':
                rem (); //add arguments here
                break;
           case '^':
                exp (); //add arguments here
                break;
           case 'L':
                log (); //add arguments here
                break;
           case '^':
                exp (); //add arguments here
                break;
           case '!':
                factorial (); //add arguments here
                break;
    }

"break" stops the switch-statement evaluating any further. Also, you need to pass the actual operands to the functions:

double plus (double Op, double Op2) //slightly optimized your plus function
{
	return (Op+Op2);
}

So in your switch, you pass the arguments to it:

switch (optor)
    {
           case '+':
                ans = plus(op1, op2);
                break;

As for a display function, you could declare it like this:

void display_equation(double left_operand , double right_operand, char operator, double answer);

You would only need to actually print out the operands, the operator and the answer in the correct order.

Hope that helps, please do let us know if you have any further questions.

All the best,
NwN

Last edited on

Excuseyou (4)

Awesome, thank you!

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Need Help on Simple calculator [Question Answered]