My first cpp app

Well at least the basics are really similar to Java. I just need to think of things to do. :dunno:

Code:

---

// Calc.cpp
// CompiledMonkey

#include "stdafx.h"

void add()
{
        float x, y;

        std::cout << "Enter first number: ";
        std::cin >> x;

        std::cout << "Enter second number: ";
        std::cin >> y;

        std::cout << x << " + " << y << " = " << (x + y) << "\n";
}

void subtract()
{
        float x, y;

        std::cout << "Enter first number: ";
        std::cin >> x;

        std::cout << "Enter second number: ";
        std::cin >> y;

        std::cout << x << " - " << y << " = " << (x - y) << "\n";
}

int main()
{
        bool flag = true;
        int option = 0;

        do
        {
                // Display menu and get option
                std::cout << "\n1: Add\n2: Subtract\n3: Exit\n\nPick an operation: ";
                std::cin >> option;

                switch(option)
                {
                        case 1:
                                add();
                                break;
                        case 2:
                                subtract();
                                break;
                        case 3:
                                flag = false;
                                break;
                        default:
                                std::cout << "Bad choice!\n\n";
                                break;
                }
        }
        while(flag);

        return 0;
}

---

Good program. But..

1. Functions are usually defined after main; prototypes are used.

2. stdafx.h is not standard C++;- use with Visual C++

Check out C++ tutorials and books.

What book are you using to help you?

Quote:

---

Originally posted by Mister C
Good program. But..

1. Functions are usually defined after main; prototypes are used.

2. stdafx.h is not standard C++;- use with Visual C++

Check out C++ tutorials and books.

What book are you using to help you?

---

1. I was thinking it was odd I couldn't have my functions below main. I'm not sure what you mean by prototypes though.

2. I just started a Win32 console application in VS.NET 2003. It started me out with that.

I'm not using any books right now. I just started coding. When I ran into a block, I did a quick Google search.

Prototypes are like:

Code:

---

#includes
int myfunc(int this, int that);//Prototype
int main(){
//Blah blah blah
}
myfunc(int this, int that){
//Blah blah blah
}

---

Oh I see. So I should make prototypes of my functions at the top?

>So I should make prototypes of my functions at the top?
After the includes and global variables(yes, I no they're bad habits).
I always do that. Looks neater. Or you could put your functions in a .h file and include that.

Yeah, I was about to ask about header files. Would a header just have the prototype or the actual implementation as well?

>>Would a header just have the prototype or the actual implementation as well?

You can do either. If your functions reference each other you should do prototypes.

Cool. Anymore advice?

Function prototypes should be placed in a header-file and the function implementation should be placed in a source-file. If your functions are used in more files, then you only need to include the header-file with the prototypes in those files.

Sounds like solid design to me. Thanks. ;)

Anyone want to comment on my code style? Am I doing anything wrong? More ideas for small time projects like this are welcome as well. ;)

This:

Code:

---

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

---

instead of:

[CODE]
#include<iostream.h>
#include<string.h>
using namespace std;
[CODE]

Leave out the .h on files, add

Code:

---

using namespace std;

---

and for older files, like stdlib.h do cstdlib.

It doesn't matter if you put your functions before or after main... but prototypes are a good idea.

A way to simplify your program:
Group the inputting of the first two numbers into a seperate function (or int main, if you prefer), instead of one copy in addition and one copy in subtraction. ie:

Code:

---

// Calc.cpp
// CompiledMonkey

#include "stdafx.h"
void add();
void subtract();
void input_two_numbers(float&, float&);

void input_two_numbers(float& x, float& y)
{
        std::cout << "Enter first number: ";
        std::cin >> x;

        std::cout << "Enter second number: ";
        std::cin >> y;
}
void add()
{
        float x, y;
        input_two_numbers(x,y);

        std::cout << x << " + " << y << " = " << (x + y) << "\n";
}

void subtract()
{
        float x, y;
        input_two_numbers(x,y);

        std::cout << x << " - " << y << " = " << (x - y) << "\n";
}

int main()
{
        bool flag = true;
        int option = 0;

        do
        {
                // Display menu and get option
                std::cout << "\n1: Add\n2: Subtract\n3: Exit\n\nPick an operation: ";
                std::cin >> option;

                switch(option)
                {
                        case 1:
                                add();
                                break;
                        case 2:
                                subtract();
                                break;
                        case 3:
                                flag = false;
                                break;
                        default:
                                std::cout << "Bad choice!\n\n";
                                break;
                }
        }
        while(flag);

        return 0;
}

---

> More ideas for small time projects like this are welcome as well.

You could do something simple like implementing a datastructure to learn about how to use the language and its language elements and constructions.

Also you should experiment a bit with classes to see what C++ and Java have common and what is different. For example see how abstract classes are implemented in C++ and how they differ from Java. And experiment a bit with inheritance.

When I started programming in Java, with a background in C++, I found a lot of things were similar. However, some things were a bit different and it is good to find out what the impact of the differences are. C++ for example allows multiple inheritance by classes, for Java you can something like that using interfaces.

CompiledMonkey,
have you learned about classes yet? If so, or when you do, you can make the calculator object oriented.

P.S.:I attached my first calculator here. Before you look at the source try adding a square root function. I didn't get to this, but you could also add powers. If you're stumped, you can use sqrt() or pwr() in math.h (or is the newer one cmath or math?)

Ok, quick question, on this line of code:

Code:

---

void inputTwoNumbers(float& x, float& y)

---

Why are there & symbols? Same goes for the prototype line.

Also, I assume you are passing the x and y by reference down to the inputTwoNumbers function. Otherwise how would the values of x and y in the add and subtract functions be getting set. Is that correct?

Quote:

---

Originally posted by Shiro
> More ideas for small time projects like this are welcome as well.

You could do something simple like implementing a datastructure to learn about how to use the language and its language elements and constructions.

Also you should experiment a bit with classes to see what C++ and Java have common and what is different. For example see how abstract classes are implemented in C++ and how they differ from Java. And experiment a bit with inheritance.

When I started programming in Java, with a background in C++, I found a lot of things were similar. However, some things were a bit different and it is good to find out what the impact of the differences are. C++ for example allows multiple inheritance by classes, for Java you can something like that using interfaces.

---

Great advice. Thank you! I'm going to do some reading, maybe beef up my Calc a little more. Then I'll get into classes, inheritance, pointers, etc. I know Java quite well, so some of this is easy. I'm not looking forward to pointers though. I've always been told that is the worst. :o

The newer is <cmath>.


You might want to use
using std::cin;
using std::cout;

if you use those very often. Sorta like the import statements in Java.

Quote:

---

Why are there & symbols? Same goes for the prototype line.

Also, I assume you are passing the x and y by reference down to the inputTwoNumbers function.

---

Those two questions kind of delete each other :). The & is what makes the parameter a reference instead of a copy.

Quote:

---

Originally posted by fuh
CompiledMonkey,
have you learned about classes yet? If so, or when you do, you can make the calculator object oriented.

P.S.:I attached my first calculator here. Before you look at the source try adding a square root function. I didn't get to this, but you could also add powers. If you're stumped, you can use sqrt() or pwr() in math.h (or is the newer one cmath or math?)

---

No, I haven't gotten to classes yet. Today was my first with C++. :) I'll download your Calc, but I want to try and add some stuff by myself first. Like you suggested. Thanks for your help!

Quote:

---

Originally posted by CompiledMonkey
Today was my first with C++. :)

---

Pretty good for your first day :D
More program ideas:
-A little game
-Learn about file i/o and make a program to write something (like a soccer schedule and email it)
-Play any card games? I made a Yu-Gi-Oh LP calculator
-Make a math program (gives you two random numbers then you multiply them and see how far you can go)

Quote:

---

Originally posted by CornedBee
Those two questions kind of delete each other :). The & is what makes the parameter a reference instead of a copy.

---

Perfect! :)

Quote:

---

Originally posted by fuh
Pretty good for your first day :D
More program ideas:
-A little game
-Learn about file i/o and make a program to write something (like a soccer schedule and email it)
-Play any card games? I made a Yu-Gi-Oh LP calculator
-Make a math program (gives you two random numbers then you multiply them and see how far you can go)

---

The game sounds cool. I've always wanted to get into games. Maybe I could start with a console based app. I dunno.

I'm certainly going to do some file IO. I've got to finish a homework assignment for my programming class (hopefully tomo), and then I'll go that next.

I just want to thank everyone that helped in this thread. Everyone was very helpful. If you guys wanna share some code you wrote when you first started or some stories, please do! :)

Here was my approach for pointers. It worked, somewhat. First, I read a book which had a chapter on them. Didn't get them. Then I read a different book. Sorta got them, but not really. Then I read The Ultimate Guide to C++ or some such book...all I remember was it was written by Ivor Horton and had a red cover. I understood them better. Then I read some other stuff, and understood them quite well. It seems that nobody can write a good enough thing on pointers, and it takes the combination of several books... Anyway, after that, I proceeded to not code much for several months because I was spending too much time with school. During that time, I managed to forget a lot of stuff with pointers. Yay. I get to learn them again. Oh well, shouldn't be hard by now.

For programs, you could make tic-tac-toe (really basic, I'm going to write a tutorial tonight probably, check the game forum later for a link), followed by pong (you might want to do something else before you do that) If you need a pong tutorial... *shameless plug* http://confuted.0catch.com/tutorials/ball/ball.html That covers ball movement. Also, you could try writing a matrix class and/or a linked list class. Those will give you some experience with arrays and pointers.

A question, why do I have to include stdafx.h? That file looks like this:

Code:

---

// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//

#pragma once


#include <iostream>
#include <tchar.h>

// TODO: reference additional headers your program requires here

---

When I try and just include iostream and tchar in my Calc.cpp file, I get "fatal error C1010: unexpected end of file while looking for precompiled header directive".

It probably has something to do with how VS handles projects. Try just creating an empty C++ project, and doing it that way. That should work, and you shouldn't need tchar.h. I don't even know what that is to be honest.

tchar.h is from the windows api. It's a type for portability between unicode and ansi.

Why can't I just include those two headers and drop the other files?

Because you told VC++ in the project options that you are using stdafx.h as the precompiled header. If you don't include it, VC++ gets confused.


The solution is to make every project an empty project and adding files yourself.

Yeah, using GCC or some other compiler, you wouldn't need stdafx.h, just iostream

Using other project settings you wouldn't need it in VC++ either.

You can try to make an ASCII rectangle-drawing program. I tried, but it went haywire.
I mean ASCII like:

Code:

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Got another idea! With file I/O, make a list of all the web sites you like.