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For Loop -> While Loop

 
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For Loop -> While Loop, conversion
aznballerlee
16 Oct, 2006 - 05:58 PM
Post #1

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Once again another question.

I want to change the inner loop from "for loop" to "while loop".
I cannot figure out my errors.

error C2065: 'j' : undeclared identifier
error C1903: unable to recover from previous error(s); stopping compilation


So I am trying to convert this "for loop":

CODE

#include <iostream>
    using namespace std;

    int main()
    {
        int len;

        cout << "Enter a number: ";
        cin >> len;

        for (int i = 0; i < len; i++)
        {
            for (int j = i+1; j < len; j++)
        {
            cout << ' ';
        }
        cout << "#\n";
        }
    }


into this (or what i have so far):

CODE

#include <iostream>
    using namespace std;

    int main()
    {
        int len;

        cout << "Enter a number: ";
        cin >> len;

        for (int i = 0; i < len; i++)
        {
        while (j < len)
        {
          int j = i+1;
          j++;
           cout << ' ';
        
        }
        cout << "#\n";
        }
    }
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Amadeus
RE: For Loop -> While Loop
16 Oct, 2006 - 06:02 PM
Post #2

g++ -o drink whiskey.cpp
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As per the error message, you will note that in the original code, you have actually declared and instantiated the variable j
CODE

int j = i+1

in the second piece of code, you are trying to use j before you declare it...it does not exist before you try and use it, so the compiler throws an error.
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aznballerlee
RE: For Loop -> While Loop
16 Oct, 2006 - 06:05 PM
Post #3

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Right, that's what I thought. Where would be the appropriate place to declare the j?
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aznballerlee
RE: For Loop -> While Loop
16 Oct, 2006 - 06:08 PM
Post #4

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I tried this code:

CODE

#include <iostream>
    using namespace std;

    int main()
    {
        int len;

        cout << "Enter a number: ";
        cin >> len;

        int j;
        for (int i = 0; i < len; i++)
        {
        while (j < len)
        {
          int j = i+1;
          j++;
           cout << ' ';
        
        }
        cout << "#\n";
        }
    }


which runs but it doesn't produce the same results as the original (with the for loops)
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Amadeus
RE: For Loop -> While Loop
16 Oct, 2006 - 06:08 PM
Post #5

g++ -o drink whiskey.cpp
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Before you use it. Declare j as an int at the top of your program, where you declare len, then set j to the value of i+1 right before you begin the while loop.
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aznballerlee
RE: For Loop -> While Loop
16 Oct, 2006 - 06:10 PM
Post #6

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Great! Thanks Amadeus for all your help! smile.gif
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