Global variable

This is a discussion on Global variable within the C++ Programming forums, part of the General Programming Boards category; hey guys, I have been told not to use global variables in my programs but now I have come accross ...

  1. #1
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    Global variable

    hey guys, I have been told not to use global variables in my programs but now I have come accross a problem. I have a boolean variable which is initlised to false and when a function is called it is set to true so when that function is called for a second time a certain action will occur. But i can't put the bool in that function other wise it will always reset to false.

    Is there anyother way round this problem other than having a global variable?

  2. #2
    Devil's Advocate SlyMaelstrom's Avatar
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    Code:
    static bool var1;
    Sent from my iPadŽ

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    nice one thanks.

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    Registered User Kurisu's Avatar
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    yep, as sly mentioned..

    A static variable is declared only once; remains active for the program life yet is only visible where it is declared.

    ex:
    Code:
    int count()
    {
      static bool status = false;  // Declared only the first time this function is called ignored each subsequent call.
    
      status = !status;
    }
    Last edited by Kurisu; 02-15-2006 at 08:05 PM.

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    Thanks for that

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    But i can't put the bool in that function other wise it will always reset to false.
    Another way: declare your boolean variable in main(), and then send it to the function as an argument. If you make the function parameter a reference, which just means you put a '&' symbol to the right of the type, then the function will be able to change the value of the variable back in main(). Here is an example:
    Code:
    #include <iostream>
    using namespace std;
    
    void myFunc(bool& aFlag, int num)
    {
    	if(aFlag)
    	{
    		cout<<num<<endl;
    	}
    	else
    	{
    		cout<<"Flag is false."<<endl;
    		aFlag = true;
    	}
    }
    
    int main()
    {
    	bool myFlag = false;
    	myFunc(myFlag, 10);
    	myFunc(myFlag, 5);
    
    	return 0;
    }
    The parameter variable aFlag becomes a synonym, or alternate name, for myFlag back in main(), and as a result myFlag and aFlag are the same thing.
    Last edited by 7stud; 02-15-2006 at 08:38 PM.

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