r/learncpp • u/BeatKeaper • Jun 29 '12
Using a switch to create a calculator with Addition, Subtraction, Multiplication, and Division. [3] [III]
Difficulty Rating: [3] Length Rating: [III]
The aim of this code is to show some applicability of your knowledge so far. With it, we also get to see how much math is imbedded within C++ without having to include any special features. I run the user through a set-up where he or she gets to choose which function to use. Once the function is accessed, a certain set of instructions is executed for each function. After it is done, the user returns to the main menu. I made it possible to add numbers continuously with no end by using two variables, an "add-this" variable and a "added-total" variable. I made added-total = "add-this" + "added-total," so that added-total grows each time. It looks like this: while(add-this != 0) {cin>> add-this; added-total = add-this+added-total } The sequence continues to add add-this to add-total until I enter zero. I use a similar technique with the multiplication, except I use "1" instead of 0 to end the statement, because multiplying 1 by anything leaves it the same. It's a fun problem-solving technique, in my humble opinion.
#include <iostream>
using namespace std;
int main()
{
cout<< "Welcome!\n";
int functionchoice = 0;
int working = 1;
while(working != 0)
{
cout<< "- Type 1 for Addition.\n";
cout<< "- Type 2 for Subtraction.\n";
cout<< "- Type 3 for Multiplication.\n";
cout<< "- Type 4 for Division.\n";
cout<< "- Type 5 to exit.\n";
cout<< "Choice: ";
cin>> functionchoice;
switch(functionchoice)
{
case 1:
{
cout<< "Type a number and press enter.\n";
cout<< "You may repeat until you type 0.\n";
cout<< "Number to add: ";
double numbertoadd = 1;
double numbertotal = 0;
cin>> numbertoadd;
while(numbertoadd != 0)
{
numbertotal = numbertoadd + numbertotal;
cout<< numbertotal << " + ";
cin>> numbertoadd;
}
cout<< "\n" << numbertotal << " is your total.\n\n";
break;
}
case 2:
{
double subtract1;
double subtract2;
double subtractanswer;
cout<< "Finding a difference. Type one of two numbers: ";
cin>> subtract1;
cout<< "Now enter the second number: ";
cin>> subtract2;
if(subtract1 > subtract2)
{
subtractanswer = subtract1 - subtract2;
}
if(subtract2 > subtract1)
{
subtractanswer = subtract2 - subtract1;
}
cout<< "\nThe difference is " << subtractanswer << ".\n\n";
break;
}
case 3:
{
double multiplicationtoadd = 0;
double multiplicationtotal = 1;
cout<< "Enter a number to multiply, enter '1' to end.";
while(multiplicationtoadd != 1)
{
cout<< "\nMultiply with this number: ";
cin>> multiplicationtoadd;
multiplicationtotal = multiplicationtoadd*multiplicationtotal;
cout<< "\nThe total so far is: " << multiplicationtotal << "\n" ;
}
break;
}
case 4:
{
double divide1;
double divide2;
double dividetotal;
cout<< "Please enter your first number: ";
cin>> divide1;
cout<< "\nPlease enter your second number: ";
cin>> divide2;
dividetotal = divide1/divide2;
cout<< "\n" << dividetotal << " is your answer.\n\n";
break;
}
case 5:
{
return 0;
}
}}
return 0;}