Thread: Loss of zero

  1. 01-31-2011 #1
    Freshquiz
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    Loss of zero

    Hi guys,

    I got a programming assignment and I am not allowed to use 'strings' to solve this specific problem I have encountered. In this program, the user inputs a fixed length number and the program collects the number via the scanf function. I needed to break the number into segments so I used division by 10^x (x varying) and also the modulus operation. The problem I have is that when I use the modulus operation and the number contains a zero, I lose that zero. I need the zero because the number is a barcode.
    For example:
    Barcode: 9484029480583
    If I wanted to extract the number 058 from that barcode (the last three numebrs minus the checksum) I would use the following operation:
    ((9484029480583)/(10))%(1000), but the problem is instead of the result being 058, I get just 58. I can overcome this problem by simply inputting a zero in front of the two numbers when using printf, but this would create extensively messy code because I would have a lot of 'if' statements (Im not allowed to use 'case' so don't go there). Is there a way that I can somehow retain that zero in front of the three number segment?
  2. 01-31-2011 #2
    Salem
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    Say
    printf( "%03d", 58 );
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  3. 01-31-2011 #3
    grumpy
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    Look up flags for the printf format string (particularly flag 0 which means "left pad with zeros rather than spaces").
    Right 98% of the time, and don't care about the other 3%.

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  4. 01-31-2011 #4
    Freshquiz
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    Thanks, but I don't think that helps me. Having a number between the integer input (%"number"d), is that different to having before or after? Sorry I have never put it in the middle. I tried it anyway, but it didn't work.
    Like I said, I could print the 0 in front by writing the code, but it would produce a massive headache of 'if' statements. I just get the feeling there is a simpler way of doing by altering the variable storing the number or something.

    I had a thought. What is it that is removing the leading zero. Is it the calculation and storing of the variable or is it the printing of the contents of the variable as an integer? Maybe we could solve it by attacking which ever one is causing it.
  5. 01-31-2011 #5
    Freshquiz
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    Ok thanks, yep I got it. Thanks to both of you. Yep I found the flags thanks.
  6. 01-31-2011 #6
    msh
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    Like I said, I could print the 0 in front by writing the code, but it would produce a massive headache of 'if' statements. I just get the feeling there is a simpler way of doing by altering the variable storing the number or something.
    Yes. Using strings.
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  7. 01-31-2011 #7
    iMalc
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    Quote Originally Posted by Freshquiz View Post
    What is it that is removing the leading zero. Is it the calculation and storing of the variable or is it the printing of the contents of the variable as an integer? Maybe we could solve it by attacking which ever one is causing it.
    Integers have no notion of characters. They just hold a 'quantity' if you will. 7, 07, and 007 don't actually constitute different whole numbers. They all represent seven whole items and thus an int holds this value of seven.
    How you format it is of course up to you. It may be seven dollars i.e. "$7.00" or seven cents ".07c" or seven O'Clock in the morning "07:00".
    Leading and or trailing zeros are just one of many things you can choose to do when formatting the value.
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