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C++ IS fun.

Posted by Tracker , 09 January 2013 · 106 views

To day I had my first "lesson" and this is what I made, which was a lot more than asked (a simple "Hello World" type program):

// ConsoleApplication2.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

//
#include "iostream"
using namespace std;

int main()
{ int in0 = 0;
int counter = 0;
cout << counter << endl;

do
{

counter = counter + 1;
if (counter == 5)
{
in0 = 1;
}
if (counter == 4)
{
cout << "Hello, this is simple for those who know what they are doing. counter = 4" << endl;
}
cout << counter << endl;
cout << "Hello, this is simple for those who know what they are doing." << endl;

}
while (in0 == 0);
system("pause");

}

Getting this to work was a b****, however. It actually stumped the instructor. The main problem? if (counter == 5) was if (counter = 5) See if you can figure out what happened

. Need less to say, I may have given some ideas to the instructor with regards to the next lesson goal.

Also:

Project1.zip (128.99K)
downloads: 2 Cover your ears.

JrMasterModelBuilder

Jan 09 2013 01:19 AM

C++ IS fun.

Just wait . . .

See if you can figure out what happened

It probably ran forever.

Tracker

Jan 09 2013 03:23 AM

Nope, it did the opposite. Debugging the counter suggested the loop ran properly, but nothing else seemed to loop. When I said guess, I mean guess what it did and why. I figured it out. My instructor did not see the mistake before I pointed it out to him. It was just one of those things that one would often miss.

Phoenyx

Jan 09 2013 11:05 AM

Nope, it did the opposite. Debugging the counter suggested the loop ran properly, but nothing else seemed to loop. When I said guess, I mean guess what it did and why. I figured it out. My instructor did not see the mistake before I pointed it out to him. It was just one of those things that one would often miss.

counter = 5 sets int counter to 5
counter == 5 checks if counter is equal to 5, and if so returns TRUE, otherwise returning FALSE. That's why, when using if statements or do { } while loops, you're supposed to use yourintegerhere == somevalue. Most compilers will catch this and return a compile error, however some may not.

A good habit to get into is planning your program out in pseudocode before beginning to write the actual program. That way you can catch these mistakes before they become a problem.

Tracker

Jan 09 2013 02:53 PM

I don't think that would have helped much here since this error occurred even with planning.

JrMasterModelBuilder

Jan 09 2013 03:39 PM

Nope, it did the opposite. Debugging the counter suggested the loop ran properly, but nothing else seemed to loop. When I said guess, I mean guess what it did and why. I figured it out. My instructor did not see the mistake before I pointed it out to him. It was just one of those things that one would often miss.

You right, I mis-read the code.

counter = 5 sets int counter to 5
counter == 5 checks if counter is equal to 5, and if so returns TRUE, otherwise returning FALSE. That's why, when using if statements or do { } while loops, you're supposed to use yourintegerhere == somevalue. Most compilers will catch this and return a compile error, however some may not.

That's acutally valid code, you can assign variables inside of an if statement. It takes the first variable and decides if it is truth-y or false-y. Take this code for example. i is set to 0 which evaluates to false, then assigned to 2 which evaluates to true.

#include "iostream"

using namespace std;

int main()
{
    int i;
    if(i = 0)
    {
        cout << "true" << endl;
    }
    else
    {
        cout << "false" << endl;
    }
    if(i = 2)
    {
        cout << "true" << endl;
    }
    else
    {
        cout << "false" << endl;
    }
}

Phoenyx

Jan 09 2013 04:16 PM

That's acutally valid code, you can assign variables inside of an if statement. It takes the first variable and decides if it is truth-y or false-y. Take this code for example. i is set to 0 which evaluates to false, then assigned to 2 which evaluates to true.

Strange. Every compiler I've used throws an error...

Tracker

Jan 09 2013 04:22 PM

MS Visual studios 2012 is what I used. Not even a warning.

Phoenyx

Jan 09 2013 06:15 PM

Must just be a Dev C++ thing then...

Tracker

Jan 09 2013 07:35 PM

Well, I just blew it and got the wrong version of MSVS 11, so now I may have to use Dev-C++.

Phoenyx

Jan 09 2013 08:42 PM

The Express Version of Microsoft Visual Studio is free, you know.

TheDoctor

Jan 10 2013 04:36 PM

[code=auto:0]

This is valid because instead of assigning just a integer, you could be assigning something a function returns, while silly because you don't accomplish much by doing it this way (which is why it's odd, you don't often see it).

C++ IS fun.

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