My command line calculator problem(s)

[Bartek Sowka]

ok my code is:

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <math.h>
using namespace std;

int startup()
{
    system("title choosing operation");
    cout << "Enter operation (add, subtract, multiply, divide,power,+,-,*,/,^)\n>";
}

double power(double a, double b)
{
    return pow(a,b);
}

double divide(double a, double b)
{
    return a / b;
}

double multiply(double a, double b)
{
    return a * b;
}

double subtract(double a, double b)
{
    return a - b;
}

double add(double a, double b)
{
    return a + b;
}

int main(int nNumberofArgs, char* pszArgs[])
{
    double A;
    double B;
    string operation;
    cout << "NOTE: If the operation doesn't exist the program will exit." << endl;
    startup();
    cin >> operation;


    if (operation == "add"||operation=="+")
    {
        system("title adding");
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << add(A,B) << endl;
        startup();
        cin >> operation;
    }
    if (operation == "subtract"||operation=="-")
    {
        system("title subtracting");
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << subtract(A,B) << endl;
        startup();
        cin >> operation;
    }
    if (operation == "multiply"||operation=="*")
    {
        system("title multiplying");
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << multiply(A,B) << endl;
        startup();
        cin >> operation;
    }
    if (operation == "divide"||operation=="/")
    {
        system("title dividing");
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << divide(A,B) << endl;
        startup();
        cin >> operation;
    }
    if (operation == "power"||operation=="^")
    {
        system("title powering");
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << power(A,B) << endl;
        startup();
        cin >> operation;
    }
    system("title invalid operation");
    cout << "Not an operation";
    system("PAUSE >nul");
    return 0;
}

This is ran in a console application using code::blocks
Everything runs/builds fine, but there are a few stuff which i can't fix, for example:

If you input the operator once, do the calculation, then try to input the same calculation again, it will say its not a valid operation.

If you input a string or anything else apart from a double it will instantly change the second number to 0 and quit the program.

And a few others I haven't discovered.

Is there any way to fix these two? I'm not asking for code, if you can specify at least one little tip, it will help me.

Thanks, Bart

[Caprico]

This happens because your program is set to execute only once.. It seems that you misunderstand how an "if" loop will work. Suppose I chose to add two numbers.

if (operation == "add"||operation=="+")   //This will check what input I gave.
    {
        system("title adding");                       //From here
        cout << "Enter first number: ";
        cin >> A;
        cout << "Enter second number: ";
        cin >> B;
        cout << add(A,B) << endl;                //Till here, is fine
        startup();                              //It calls startup function, prints some stuff.
        cin >> operation;                          //Asks for input again
    }                                            //End of "if" loop 

At this point your program ends. You understand what is going wrong?

So instead, use a while loop, like so:

int main(int nNumberofArgs, char* pszArgs[])
{
    double A;
    double B;
    string operation;
    cout << "NOTE: If the operation doesn't exist the program will exit. Otherwise, press "q" to exit." << endl;
    startup();
    cin >> operation;

    while (operation!="q")
    {
       //The rest of the code here. (That is, check what user wants to do, the usual)(Line 48-102 of your program here)
     }

Hope this helps... :)

[Bartek Sowka]

THANK YOU!
YOU ARE A HERO!
I just need an anwser to my second question. Which I just think I can solve.
EDIT: I can't

[Bartek Sowka]

bump

[Bartek Sowka]

bump

[Bartek Sowka]

bump

[Wisely Done]

Not sure if it works, but try using stringstream.

Something like this might work:

Instead of this:

int number1;
cin >> number1;

Use this:

int string1;
int number1;
getline(cin, string1);
stringstream(string1) >> number1;