how to access local variables outside loops?

This is a discussion on how to access local variables outside loops? within the C++ Programming forums, part of the General Programming Boards category; Hi again to all. I tried to use google before asking dumb questions but i still need to ask one. ...

  1. #1
    Registered User cdkiller's Avatar
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    Question how to access local variables outside loops?

    Hi again to all. I tried to use google before asking dumb questions but i still need to ask one. I just did a lot of reading about pointers and referencing to try help my cause but my efforts were futile. i have a do while loop and within that has a while loop. now part of the condition for the outer do while loop lies within the interior while loop and the outer loop cant see the variables inside the while loop. i will paste part of the code here:

    Code:
    do
    some other code here, bla bla dont want to waste forum space, lol.
    while (pos != string::npos) 
    		{
    			cout << "Found space or dot at: " << pos << endl;
    			pos = name.find_first_of(" .", pos + 1);
    			  
    		}
    	} while ((name_length=0) && (pos !=0));
    that tells me pos undeclared identifier. i noticed that every example i saw of pointers etc used integers and not strings so i do not know what to do.

  2. #2
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    The inner loop isn't the problem. The variable you use to control the do while loop needs to be declared outside of that loop. You didn't post the declaration of pos, but presumably it is inside the bla bla part. Move it to before the do.

    Don't forget to re-initialize it at its current location if necessary for each iteration of the do while loop.

  3. #3
    Registered User cdkiller's Avatar
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    thanks, that solved my problem. after a while though i realised it was a bad idea to use pos as the condition so instead i put in another var to indicate the number of invalid characters, but the same principle i applied to it by making sure to declare it before the do.

    but i am still curious as to if its possible to use something like pointers so as to not have too many global vars and thus have more efficient code?

  4. #4
    carry on JaWiB's Avatar
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    If I understand you correctly, the variables don't need to be "global" They can be local to the function that you're in. You can also add an extra scope if you wish, eg:
    Code:
    {
      int pos = 0;
      
      do
      {
        //...
      } while(/*...*/);
    
    }
    //pos out of scope
    "Think not but that I know these things; or think
    I know them not: not therefore am I short
    Of knowing what I ought."
    -John Milton, Paradise Regained (1671)

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