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Getting an integer with only using getchar()

This is a discussion on Getting an integer with only using getchar() within the C Programming forums, part of the General Programming Boards category; I need to get an integer number with only using getchar() and without pre knowing the number of digits in ...

  1. #1
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    Getting an integer with only using getchar()

    I need to get an integer number with only using getchar() and without pre knowing the number of digits in the integer.
    And I cannot use strings or arrays.

    Any ideas?

    Thank you

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    Read in a character. if it's a digit, process it; if it's not, you're done.

    Presumably you know how, if you already have 6, and then you see a 4, how to (numerically, not in terms of strings) turn that into 64, and then turn that into 644 when another 4 comes in, etc. (If not, look up "place value".)

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    Thank you tabstop

    I don't know how I have looked for "place value", yield nothing.

    could you please direct me to a link or somethin.

  4. #4
    and the Hat of Guessing tabstop's Avatar
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  5. #5
    TEIAM - problem solved
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    I'm going to enter the number 1024 - break down the problem...

    1 Value entered so far is 1
    0 Value entered so far is 10
    2 Value entered so far is 102
    4 Value entered so far is 1024

    Have a look at the number entered so far - There is a algorithm for adding a new digit. Ask yourself what is happening to the number each time a new digit is entered.

    Every time a new character is entered, you need to valadate it (make sure it is a number), and then enter it into your algorithm for adding a new digit.
    King Mir likes this.
    Fact - Beethoven wrote his first symphony in C

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