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[Tut]C++ Truth, branching and other game loop: Guess my number


ExTrEmEDwarf

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Well recently i started reading e-books about C++.

I started making mini and easy programs and im still on start but i think im gonna be way better on next days.

 

So, here's a tutorial about a score rater, running on cmd.

 

First of all u need to have a C++ application. Im using CodeBlocks, since i got some problems on Microsoft Visual ++ 2008.

 

Anyway, lets start.

 

Make a CLEAN project from file > new > project.

 

After this start making your program.

 

//Score Rater

 

#include <iostream>

using namespace std;

 

int main()

{

   int score;

   cout << "Enter your score: ";

   cin >> score;

 

   if (score > 500)

       cout << "\nYou got over 500. Nice score.\n";

   else

       cout <<"\nYou got 500 or less. Nothing to brag about.\n";

 

   return 0;

}

 

 

 

 

If score is greater than 500, the message you got over 500... is displayed.

 

   if (score > 500)

       cout << "\nYou got over 500. Nice score.\n";

 

The else clause provides a statement for the program to branch to the if the condition is false. So if (score > 500) is false, then the program skips the first message and instead displays the message, You got 500 or less...

 

   else

       cout <<"\nYou got 500 or less. Nothing to brag about.\n";

 

Watch out, because an else clause associates with its nearest preceding if. This can lead to logical errors and unintended results if you are not careful. Here's a bit of new code (not part of the score rater program) to show you what i mean:

 

   if (false)

       if (true)

               cout << "This will never be displayed.";

   else

       cout << "This will always be displayed.";

 

At the first glance, you might think that the message, This will always displayed, will always be displayed. But in fact the code displays nothing because the else clause is not associated with the if (false); it is associated with if (true). By adding a little whitespace, you can see how the code really works

 

   if (false)

       if (true)

               cout << "This will never be displayed.";

   else

               cout << "This will always be displayed.";

 

 

I havent changed the meaning of the code (Remember whitespace is just a convenience for us humans), but i've made the meaning clearer. Because the outer if statement never executes its body, no message is ever displayed.

 

However i can solve the problem with a pair of curly braces.

 

   if (false)

{

       if (true)

               cout << "This will never be displayed.";

}

   else

               cout << "This will always be displayed.";

 

As a result, the inner if statement is set off in its own little world (called a scope) inside the block, and the else clause associates with if (false). Now the code will always display the message, This will always be displayed.

 

The guide is not 100% mine, some parts are from the book. I dont have the books name so i cant give credits ;]

 

Results of the main program;

After compiling a cmd window will pop up and it will ask you for the score.

 

ephtp2.jpg

 

If u write a score less than 500 then u will see this result:

 

2nv9fdx.jpg

 

If u write a score above than 1000 then u will see this result:

 

2nkv3g4.jpg

 

 

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im thinking to start C++ but anyway if you want learn c++ you will be learn

for first steps in C++ this tutorial is good gratz ;)

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well yes i remember that,and it's pretty good to learn the if else

btw a nice one would be to make the computer guess your number and print out his tries

you are gonna see how fast it work :P

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