Outline · [ Standard ] · Linear+ Simple Console Calculator, C++

Ok first I'm going to teach you how to create a console based calculator :blink:

First your going to need Dev-C++ which you can get here

Now that you've gotten that installed you will now be able to create your handy-dandy-programs.

Now click File > New > Project. Then select Console Application and name it "Calculator" and click ok.

Now when you start off you will see this

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   system("PAUSE");
   return EXIT_SUCCESS;
}

Right now that looks like probably complete jibberish and it pretty much is, but I'm going to explain part of it.

#include <cstdlib> and #include <iostream> are "includes" which are used to include files in the program so you can use commands, and you can create your own includes to create your includes.

I myself have absoloutly no idea what using namespace std; does. :P

int main(int argc, char * argv[]) tells the compiler that it is the main part of the program, but I don't know what the int argc stuff is... Arent I such a great teacher? Also, the { basicly tells thats were the int main starts, and the } tells were it ends.

system("PAUSE"); and return EXIT_SUCCESS; tell the program to pause after everything is done and displays "Press any key to continue...".

So now you probably don't get a word of anything I'm saying because I am a horrid teacher, but if you did get any of that then YAYYY! Ok, now this is a pretty stupid program because it does nothing right? Well by the end of this tutorial we will have made a calculator!

Ok the first command i must show you is cout. It is used to display messeges in the console.

So now change your program to this

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
cout<<"Welcome to my uber l33t calculator";
   system("PAUSE");
   return EXIT_SUCCESS;
}

You may have noticed that all of the lines in the main part of the program have a ; after everything, this is so because it tells the compiler that a new line is being started. So now your program will display "Welcome to my uber l33t calculator" Also, you can create a new line using "\n" You can try it out and watch it for yourself. I also highly reccomend that you manually type the commands in rather than copy + paste because it helps you remember the commands. Also don't forget the ; your program will get errors if you forget it!

The next thing I'm going to show you is how to declar a integer. A integer is a variable that holds the value of a number.

Now change your program to this

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   int num;
   cout<<"Welcome to my uber l33t calculator";
   system("PAUSE");
   return EXIT_SUCCESS;
}

Now we have declared num, but it doesn't equal anything so now we must give it a value. To do this we do the following

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   int num;
   num = 7;
   cout<<"Welcome to my uber l33t calculator";
   system("PAUSE");
   return EXIT_SUCCESS;
}

Now num equals 7 :), now I will show you how to display it. When you display variables with the cout command you do not need quotes. So type the following.

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   int num;
   num = 7;
   cout<<"Welcome to my uber l33t calculator\n";
   cout<<num;
   cout<<"\n";
   system("PAUSE");
   return EXIT_SUCCESS;
}

This will now display num and the \n will make some spaces so it looks less confusing :)

They're is also anather way to give num a value, but asking the user for an input. We do this by using the cin command. So change your program to this.

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   int num;
   cout<<"Welcome to my uber l33t calculator\n";
   cout<<"Enter a number\n";
   cin>>num;
   cout<<"You entered:\n";
   cout<<num;
   cout<<"\n";
   system("PAUSE");
   return EXIT_SUCCESS;
}

This will allow the user to enter a number and then be displayed. Notice that in cin you use >> unlike in cout you use << .

Now I will teach you how to use the mathmatical operator addition. Now change your program to this.

CODE

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
   int num;
   int numtwo;
   cout<<"Welcome to my uber l33t calculator\n";
   cout<<"Enter a number\n";
   cin>>num;
   cout<<"You entered:\n";
   cout<<num;
   cout<<"\n";
   numtwo = num + 7;
   cout<<num;
   cout<<" + ";
   cout<<" 7 ";
   cout<<" = ";
   cout<<numtwo;
   system("PAUSE");
   return EXIT_SUCCESS;
}

And now you auctually know anough to make a addition calculator. In this tutorial I will not show you how to do this because I think the best way for you to learn is just to experiment :D

This post has been edited by Weebs: Jun 14 2005, 03:07 AM

OK.

I'll explain somthing about namespaces in C++.

It's basically a "space of names". LOL

If you didn't have "using namespace std;" you would have to type something like std::cout<<"someshit";


Now:
int main(int argc, char * argv[])
int argc is the ARGument Count
char* argv[]/char** argv/char argv[][] is the ARGument Vector.
argc is self explanatory
argv is an array of strings provided in the command line.

eg. If it was invoked with "someprog a b c"

argv[0] would be "someprog"
argv[1] would be "a"
argv[2] would be "b"
argv[3] would be "c"

Enjoy.

Very nice weebs, great work ;)

Yeh, Biggest coding tutorial so far and first of C++ i think. :D

Thanks :) I just started C++, so I really don't know much beond integers and strings :(

Keep looking at thoose tutorials, soon you'll know the whole language. :D

Google Teach yourself C++ in 21 days.
The first result

didnt turn out right for me,but then again i have no knowlege of c++ :P im gonna learn it now though :)

I also need to edit some of the code in the turoial, I messed up somewere in the coding, but I can't figure out what is improper in the code...

I also need to edit some of the code in the turoial, I messed up somewere in the coding, but I can't figure out what is improper in the code...

CryptWizard will help you, he will kno what the problem is for sure, if you pm him im fairly sure he'll help you :)

Found out, you need to compile it? when i try to, it comes out as a error.

Compiler: Default compiler
Building Makefile: "C:\Documents and Settings\James\Desktop\Makefile.win"
Executing make...
make.exe -f "C:\Documents and Settings\James\Desktop\Makefile.win" all
make.exe: *** No rule to make target `main.exe', needed by `main.o'. Stop.

Execution terminated

I also need to edit some of the code in the turoial, I messed up somewere in the coding, but I can't figure out what is improper in the code...

I think its

CODE

  int numtwo = num + 7;

cuz it wont let me compile it cuz of that.

This post has been edited by Brooksie: Jun 12 2005, 11:03 AM

Hey, your right it is lol :P

change int numtwo = num + 7; into

numtwo = num + 7;

Yay it works now!

I myself have absoloutly no idea what using namespace std; does.

It imports the std library namespace...