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whileloop/running total problem

This is a discussion on whileloop/running total problem within the C Programming forums, part of the General Programming Boards category; hi i have been asked to input 2 integers, a drivers MILES and LITRES of fuel they have used.. i ...

  1. #1
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    whileloop/running total problem

    hi i have been asked to input 2 integers, a drivers MILES and LITRES of fuel they have used.. i am then meant to printf the miles per litre for that specific entry AND a running total of the combined MPL's added so far...

    Code:
    #include <stdio.h>
    
    int main( )
    {
    int miles;
    int litres;
    int tanks;
    int mpl;
    int totalmpl;
    int counter;
    
    while ( miles > 0, counter++ ) {
            printf("please enter the amount of miles you have driven, alternatavely, press 0 to finish the script.\n");
            scanf("%d", &miles);
    
            printf("please enter the amount of litres you used\n");
            scanf("%d", &litres);
    
            mpl=miles/litres;
    
            printf("the number of miles per litre you have gained is:%d\n", mpl);
    
            while (counter > 1)
                    {
                    totalmpl=mpl+mpl;
                    printf("the total running miles per litre is:%d\n", totalmpl);
                    }
    }
       return 0;
    
    }
    this outputs nothing, if anyone can help i would be delighted. THANKS

  2. #2
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    FYI: You code has no running total in it.

    Code:
    totalmpl=mpl+mpl;
    With the idea that you want a running total.

    Try this instead

    Code:
    totalmpl=totalmpl+mpl;
    Edit: Your code makes little sense to me.

    Code:
    while (counter > 1)
    Is there any reason to believe the value of counter is changing inside the loop?
    I say no, therefor the loop will never run or be endless!

    Tim S.
    Last edited by stahta01; 01-22-2012 at 08:08 AM.
    "Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the universe trying to produce bigger and better idiots. So far, the Universe is winning." Rick Cook

  3. #3
    spurious conceit MK27's Avatar
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    while ( miles > 0, counter++ )
    Since miles is uninitialized at this point, it is just as likely to be negative as positive. You need to initialize it to 1 or something first. The same is even more true for counter, altho I actually don't see counter as serving any useful purpose here. Just add mpl to total (total should be initialized to 0 -- that's three uninitialized variables that need to be, tch) and get rid of counter.
    stahta01 likes this.
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    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

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