Thread: Basic calculator program in C++

Here is what I came up with this might help yea some.

Code:

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


void diviminus(string );
void multiplus(string );
void calc();

int main() 
{
    string a;

    cout << "Do you wish to use the Calculator? Y/N: ";
    cin >> a;
    if (a == "Y" || a == "y") 
	{
          while (a == "Y" ||a == "y") 
          {
                calc();
                cout << "Would you like to use the calculator again? Y/N: ";
                cin >> a;
          }
    }
    else 
	{
         cin.ignore(80,'\n');
         return 0;
    }
}

void multiplus(string cal) 
{
       float a;
       float b;
       float c;
       
       if (cal == "multiply" || cal == "Multiply") 
	   {
          cout << "Input a number: ";
          cin >> a;
          cout << "Input a second number: ";
          cin >> b;
          c = a * b;
          cout << a << " times " << b << " equals " << c << ".";
          cin.ignore(80,'\n');
          cin.get();
       }
       else if (cal == "add" || cal == "Add") 
	   {
          cout << "Input a number: ";
          cin >> a;
          cout << "Input a second number: ";
          cin >> b;
          c = a + b;
          cout << a << " plus " << b << " equals " << c << ".";
          cin.ignore(80,'\n');
          cin.get();
       }
}

void diviminus(string cal) {
       float a;
       float b;
       float c;
       
       if (cal == "divide" || cal == "Divide") {
               cout << "Input a number: ";
               cin >> a;
               cout << "Input a second number: ";
               cin >> b;
               c = a / b;
               cout << a << " divided by " << b << " equals " << c << ".";
               cin.get();
       }
       else if (cal == "subtract" || cal == "Subtract") {
            cout << "Input the number you want to subtract from: ";
            cin >> a;
            cout << "Input the amout you with to subtract: ";
            cin >> b;
            c = a - b;
            cout << a << " minus " << b << " equals " << c << ".";
            cin.ignore(80,'\n');
            cin.get();
       }
}

void calc() 
{
    string cal;
    int cas;
    
    cout << "Do you want to add, subtract, multiply, or divide?\n";
    cin.ignore(80,'\n');
    cin >> cal;
    if (cal == "add" || cal ==  "Add") 
	{
         multiplus(cal);
    }
    else if (cal == "subtract" || cal ==  "Subtract") 
	{
         diviminus(cal);
    }
    else if (cal == "multiply" || cal ==  "Multiply") 
	{
         multiplus(cal);
    }
    else if (cal == "divide" || cal == "Divide") 
	{
         diviminus(cal);
    }
	else
	{
          cout << "I'm sorry, please try again.";
          calc();
    }
}

Code works perfectly now, thanks! Now how would you suggest I make it so you can add as many numbers as you want into the calculations? Like you could input

4 5 7 2 10

and it would output the sum of 4 plus 5 plus 7 plus 2 plus 10, and yet could input

8 1 3 10 2 6 8

without messing up the innards of the code?

Well if you were going to do that would all the numbers be input at the same time or would your output looks somethng like:

Code:

Do you want to add, subtract, multiply, or divide?
add
Input a number: 5
Input a number: 6
5 plus 6 equals 11
do you want to add another number? Y
Input a number: 7
11 plus 7 equals 18
do you want to add another number? N

Or what kind of formating do you want?

It wouldn't be much of a code change... you would use recursive calls to do that.... do you need an example?

Yea you can use a while loop :P was thinking a bit differently and in this case a while would be more efficent I think... Here is an example for a recursive call in case you want to play with it some:

Code:

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

void recursivefunction(int );

int main()
{
   recursivefunction(x);
}


void recursivefunction(int x)
{
   int y;
   string a;
   cout<<"Enter a number: ";
   cin>>y;
   cout<<x<<" plus "<<y<<" equals "<<x+y;
   cout<<"Do you want to add another number? ";
   cin>>a;
   if(a == "y" || a == "Y")
   {
      recursivefunction(x+y);
   }
}

The limit of a recursive function is the amount of RAM in the computer since each call takes a little bit more data... modulus is used with the syntax

Code:

a = b%c;

it will give you the remander if b was divided by c.

It is also used in generating random numbers as an example:

Code:

.
.
.
int randomnumber;
srand(clock());
randomnumber = 1+rand()%100;     //this is a number between 1 and 100
randomnumber = 25+rand()%76;     //this is a number between 25 and 100
.
.
.

Code:

c %= b;

this is equivalent to the statement:
If it even compiles I have never used it like that...

Code:

c = c%b;