help

[gitelmana]

it runs, but in a loop...

#include <iostream>
#include <math.h>

using namespace std;

int a = 1;
double x;
double y;
int c;
double sum;
int z;
int u;
int q;
int w;
int r;
int e;
int der1 = q * e;
int der2 = e - 1;
int der3 = w *r;
int der4 = r - 1;



int multip()
{

	cout << "please chose a number to multiply" << endl;
	cin >> x;
	cout << "the other number too" << endl;
	cin >> y;

	sum = x * y;

	cout << "the result is " << sum << endl;
	return 0;
}





int division()
{
	cout << "please chose a number to divide" << endl;
	cin >> x;
	cout << "pleas decide a number to divide by" << endl;
	cin >> y;

	sum = x / y;

	cout << "the result is " << sum << endl;
	return 0;


}

int sub()
{
	cout << "please chose a number to subtract" << endl;
	cin >> x;
	cout << "pleas decide a number to subtract by" << endl;
	cin >> y;

	sum = x - y;

	cout << "the result is " << sum << endl;
	return 0;
}

int add()
{
	cout << "please chose a number to add" << endl;
	cin >> x;
	cout << "pleas decide a number to add by" << endl;
	cin >> y;

	sum = x + y;

	cout << "the result is " << sum << endl;
	return 0;
}

int root()
{
	cout << "please chose a number to square root" << endl;
	cin >> x;
	sum = sqrt(x);

	cout << "the result is " << sum << endl;
	return 0;
} 

int log()
{
	cout << "please chose a number to log (natural log)" << endl;
	cin >> x;
	sum = log10(x);

	cout << "the result is " << sum << endl;
	return 0;

}

int expo()
{
	cout << "please chose a base" << endl;
	cin >> x;
	cout << "please chose a exponent" << endl;
	cin >> y;

	sum = pow(x, y);

	cout << "the result is " << sum << endl;
	return 0;

}

int main()
{

	while (a <= 1)
	{



		cout << "please chose an operation: for mult. put 1, for dev but 2 for sub put 3, for addition put 4, square root is 5, log is 6, exponents is 7, enter 8 for derivative" << endl;

		cin >> c;

		if (c == 8) {


			cout << "press 1 for product" << endl;
			cin >> u;
			// multiplication		

			if (u == 1)
			{


				// v'
				cout << "for product enter it in the form of ax^n" << endl;
				cout << "first  enter a then enter n" << endl;
				cin >> q;
				cin >> e;


				//u'
				cout << "now enter the second equation in the same format" << endl;
				cin >> w;
				cin >> r;




				cout << "the derivative is: (" << q << "x^" << e << ")" << der3 << "x^" << der4 << "+(" << w << "x^" << r << ")" << der1 << "x^" << der2 << endl;
			}




		}




		if (c == 2)
		{
			int division();
		}

		if (c == 1)
		{
			int multip();
		}

		if (c == 3)
		{
			int sub();
		}

		if (c == 4)
		{
			int add();
		}
			if (c == 5)
			{
				int root();

			}
			if (c == 6)
			{
				int log();

			}

			if (c == 7)
			{
				int expo();

			}

			cout << "Press 1 followed by enter to begin the calculator, or enter 2 to end" << endl;
			cin >> a;
		}


	}

[salem c]

Well at least you managed to use code tags.

But....
http://www.catb.org/esr/faqs/smart-questions.html#bespecific

		if (c == 7)
			{
				int expo();

			}

This is just another prototype for expo();
If you want to actually call it, then do something like
int result = expo();

int z;
int u;
int q;
int w;
int r;
int e;
int der1 = q * e;
int der2 = e - 1;
int der3 = w *r;
int der4 = r - 1;

Pick MEANINGFUL variable names.

Also, the der variables are NOT automatically recalculated each time you assign say a new value to q.

[dhayden]

Use a switch statement instead of a bunch of if's.

I'd write functions to prompt for 1 and 2 variables and call them in each case. This will eliminate lots of redundant code.

Here is a subset of your program that demonstrates what I mean.

#include <iostream>
#include <math.h>

using namespace std;

void get1(double &a, const string &prompt)
{
    cout << prompt << '\n';
    cout << "please enter a: ";
    cin >> a;
}

void get2(double &a, double &b, const string &prompt)
{
    get1(a, prompt);   // Call get1() to get the first value.
    cout << "please enter b: ";
    cin >> b;
}


int
main()
{
    double a,b;
    int c;
    
    while (true) {

	cout <<
	    "please chose an operation: for mult. put 1, for dev but 2 for sub put 3, for addition put 4, square root is 5, log is 6, exponents is 7, enter 8 for derivative"
	    << endl;
	cout << "Press ctrl-d to exit\n";
	cin >> c;
	if (!cin) break;	// exit the loop on error or end of file

	switch(c) {
	case 8:
	case 6:
	case 7:
	    cout << "Not yet implemented";
	    break;
	case 2:
	    get2(a,b, "Computing a/b");
	    cout << "result is " << a/b << '\n';
	    break;

	case 5:
	    get1(a, "Computing sqrt(a)");
	    cout << "result is " << sqrt(a) << '\n';
	    break;

	}
    }
}

[gitelmana]

I've never heard if cases and switch... I'll do more research, thank you! This is for my AP computer science exam.