Making a calculator.

[Amnesia]

Hi, I've been making a calculator that is able to process decimals. I'm a noob, but would like some help on this matter:

These are the errors:

1>3.cpp(30): error C2065: 'dValue1' : undeclared identifier
1>3.cpp(30): error C2065: 'chOperator' : undeclared identifier
1>3.cpp(30): error C2065: 'dValue2' : undeclared identifier
1>3.cpp(30): error C2065: 'dResult' : undeclared identifier
1>3.cpp(37): error C2065: 'chOperator' : undeclared identifier
1>3.cpp(39): error C2065: 'chOperator' : undeclared identifier
1>3.cpp(41): error C2065: 'chOperator' : undeclared identifier
1>3.cpp(43): error C2065: 'chOperator' : undeclared identifier
1>3.cpp(57): error C2065: 'Operator' : undeclared identifier

This is the code:

#include "stdafx.h"
#include <iostream>


double GetNumber() // får tallene
{
using namespace std;

cout << "Venligst skriv et tal (decimaler er tilladt): ";
double dValue;
cin >> dValue;

return dValue;
}

char GetOperator()
{
using namespace std;

cout << "Indtast en operator (*, /, - eller +): ";
char y;
cin >> y;
return y;
}

void PrintResult(double x)
{
using namespace std;

cout << dValue1 << " " << chOperator << " " << dValue2 << " = " << dResult << endl;
}

double CalculateResult(double w, char u, double o) // udregner tallene
{
using namespace std;

if (chOperator== '+')
return w + o;
if (chOperator== '-')
return w - o;
if (chOperator== '*')
return w * o;
if (chOperator== '/')
return w / o;
}

int main()
{
using namespace std;

double dValue1 = GetNumber(); // får det første tal

char chOperator = GetOperator(); // får operatoren

double dValue2 = GetNumber(); // får det andet tal

double dResult = CalculateResult(dValue1, Operator, dValue2); // får det andet tal

PrintResult(dResult);

cin.clear();
cin.ignore(255, '\n');
cin.get();
return 0;
}

[coder777]

'dValue1' and all those variables are local variables. They cannot be used outside the function (main()) where they're defined.

[Amnesia]

But how come this code works fluently? To me it seems like they're almost the same, only it's working with int instead of float.


#include "stdafx.h"
#include <iostream>
using namespace std;

int GetValue()
{
cout << "Skriv venligst en vaerdi: ";

int nValue;
cin >> nValue;
return nValue;
}

char GetOperator()
{
cout << "Indtast venligst en operator (*, /, -, +): ";

char chOperator;
cin >> chOperator;
return chOperator;
}

int CalculateResult(int nX, char Operator, int nY)
{
if (Operator=='+')
return nX+nY;
if (Operator=='-')
return nX-nY;
if (Operator=='*')
return nX*nY;
if (Operator=='/')
return nX/nY;

return 0;
}

void PrintResult(int nResult)
{
cout << "Dit resultat er: " << nResult << endl;
}
int main()
{
int nInput1 = GetValue(); // Får værdien

char Operator = GetOperator(); // Får operatoren

int nInput2 = GetValue(); // Får den anden værdi

int nResult = CalculateResult(nInput1, Operator, nInput2); // Udregner det og giver det en den midligeretidligere værdi nResult

PrintResult(nResult);
}

[coder777]

Please use code tags: [code]Your code[/code] http://www.cplusplus.com/articles/o13hAqkS/

The difference is the variables the compiler complains about.

void PrintResult(double x)
{
using namespace std;

cout << dValue1 << " " << chOperator << " " << dValue2 << " = " << dResult<< endl;
}

vs

void PrintResult(int nResult)
{
cout << "Dit resultat er: " << nResult << endl;
}

if you want to use a variable in more than 1 function you must define this variable outside any function but before the first function that uses the variable

[Amnesia]

Alright I'm super confused now. The calculator works - somewhat. But whenever I add the numbers, let's say 1 + 2 it gives me the result 44??! Where did I go wrong? Any help is much appreciated!

// nytforsog.cpp : main project file.

#include "stdafx.h"
#include <iostream>
using namespace std;

int main()
{
	cout << "Gimme a number: ";
	double x;
	cin >> x;

	cout << "Gimme an operator: ";
	char y;
	cin >> y;

	cout << "Gimme another number: ";
	double w;
	cin >> w;

	if (y=='+')
		cout << x << " " << y << " " << w << " = " << x + y << endl;
	if (y=='-')
		cout << x << " " << y << " " << w << " = " << x - y << endl;
	if (y=='*')
		cout << x << " " << y << " " << w << " = " << x * y << endl;
	if (y=='/')
		cout << x << " " << y << " " << w << " = " << x / y << endl;

		
	cin.clear();
	cin.ignore(255, '\n');
	cin.get();
	
	return 0;
}

[coder777]

x + y where y is the '+' sign (which is ascii 43). so it is 1 + '+' or 1 + 43 hence = 44

it must be x + w

[GraemeR]

Hi

Have you considered a test if none of the 4 operators is entered to throw an error or ask for re entry?

Graham