a problem with the check digi in the isbn prog

This is a discussion on a problem with the check digi in the isbn prog within the C Programming forums, part of the General Programming Boards category; this is the first problem set in cs50 i think that ihave a problem with thefor loop plz help this ...

  1. #1
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    a problem with the check digi in the isbn prog

    this is the first problem set in cs50

    i think that ihave a problem with thefor loop
    plz help

    this is my code for isbn.c

    Code:
    #include <cs50.h>
    #include <stdio.h>
    
    int
     main( int argc , char *argv[])
     {
    
    printf("isbn-num :");
    long long isbnum = GetLongLong();
    int sum=0;
    int i;
    
    for ( i= 10;i>0;i--)
    
    {
    int ldigi = (isbnum % 10) ;
    
    isbnum = (isbnum-ldigi);
    
    printf("%d \n",isbnum );
    
    
    }
    
    }
    the code decremented by 9 ? when i give 5641615 the prog give me 5641606
    thanx
    Last edited by polypic; 03-16-2010 at 11:46 AM.

  2. #2
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    If you want to "peel off" digits, then replace the subtraction, with division by 10.

  3. #3
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    whati want to say here that
    when there isno for loop
    i inter
    :11111
    gives me
    11110
    okay

    put with the loop gives my some thing like this
    even if i`m peeling off digit`s with division by 10


    C:\esso>a.exe

    isbn-num :11111

    1717988029
    -257697927
    2121713855
    1500661574
    1438556346
    -715137825
    -501010513
    379395678
    37939567
    862787415







    why ?

  4. #4
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  5. #5
    and the hat of wrongness Salem's Avatar
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    > int ldigi = (isbnum % 10) ;
    > isbnum = (isbnum-ldigi);
    So next time around, ldigi will be 0

    isbnum /= 10;
    is needed as well, if you want to peel each digit off in turn.


    > printf("%d \n",isbnum );
    It's the wrong format for printing a long long
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  6. #6
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    thanx salem
    okay
    nowi`m printing long long like this
    > printf("%lld \n",isbnum );
    but still thesame strange result

  7. #7
    and the hat of wrongness Salem's Avatar
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    Post ALL of your latest code, not one random line.

    Also, are you using the Mingw compiler underneath dev-c++ (and perhaps even code::blocks)?
    You might have to use the Microsoft format specifiers for long long
    Format Specification Fields: printf and wprintf Functions (CRT)
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  8. #8
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    thanx
    here is the code

    Code:
    #include <cs50.h>
    #include <stdio.h>
    
    int
     main( int argc , char *argv[])
     {
    
    printf("isbn-num :");
    long long isbnum = GetLongLong();
    int sum=0;
    int i;
    
    for ( i= 10;i>0;i--)
    
    {
    int ldigi = (isbnum % 10) ;
    isbnum/=10 ;
    
    printf("%lld \n",isbnum );
    
    
    }
    
    }
    & yes i`m using Mingw
    i don`t know how to use Microsoft format specifiers for long long ?
    thanx

  9. #9
    CSharpener vart's Avatar
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    microsoft format would be %I64d
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  10. #10
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    Or %lld works too.

  11. #11
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    plz help me with this
    i can`t get any much farther here is the code

    Code:
    #include <cs50.h>
    #include <stdio.h>
    
    int
     main( int argc , char *argv[])
     {
    
    printf("isbn-num :");
    long long isbnum = GetLongLong();
    int sum=0;
    int i;
    
    for ( i= 10;i>0;i--)
    
    {
    isbnum/=10 ;
    
    printf("%I64d \n",isbnum );
    
    
    }
    
    }

    & here is theouput


    C:\esso>gcc isbn.c -lcs50

    C:\esso>a
    isbn-num :454854854
    862789023206188871
    86278902320618887
    8627890232061888
    862789023206188
    86278902320618
    8627890232061
    862789023206
    86278902320
    8627890232
    862789023




    plz help

  12. #12
    and the Hat of Guessing tabstop's Avatar
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    If your for loop only runs 10 times, then you'll only get 10 lines of answers.

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