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Thread: What is \xb8\x00\x00\x00.... in C language

  1. #1
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    What is \xb8\x00\x00\x00.... in C language

    Hi friends,

    I was reading an article and I found this line of code for a C program.

    Code:
    static char abc[7]="\xb8\x00\x00\x00"
                               "\xff\xe0"
    What is meaning of the code in double quotes?

  2. #2
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    Re: What is \xb8\x00\x00\x00.... in C language

    It's a series of hexadecimal escape sequences. Each '\xNN' represents the character with value NN in hexadecimal.

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    Re: What is \xb8\x00\x00\x00.... in C language

    Whoever wrote this code has no idea what they are doing. There is no guarantee that 0xb8, 0xff and 0xe0 will fit in a char.
    「明後日の夕方には帰ってるからね。」


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    Re: What is \xb8\x00\x00\x00.... in C language

    Quote Originally Posted by Bachstelze View Post
    Whoever wrote this code has no idea what they are doing. There is no guarantee that 0xb8, 0xff and 0xe0 will fit in a char.
    If it is declared unsigned, shouldn't it work. Also does C declare a char as signed when there is no unsigned or signed prefix in the declaration.
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    Re: What is \xb8\x00\x00\x00.... in C language

    Quote Originally Posted by alegomaster View Post
    If it is declared unsigned, shouldn't it work. Also does C declare a char as signed when there is no unsigned or signed prefix in the declaration.
    It is implementation-defined whether char actually means signed char or unsigned char.

    EDIT: It will work if it is declared unsigned, yes. Here it is not.
    Last edited by Bachstelze; February 28th, 2012 at 11:36 PM.
    「明後日の夕方には帰ってるからね。」


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    Re: What is \xb8\x00\x00\x00.... in C language

    Quote Originally Posted by Bachstelze View Post
    It is implementation-defined whether char actually means signed char or unsigned char.
    Would I be right in thinking that passing compiler options would set the default char signed-ness? So...the article could suggest passing the -funsigned-char argument to gcc...but maybe I'm wrong.

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    Re: What is \xb8\x00\x00\x00.... in C language

    Quote Originally Posted by MG&TL View Post
    Would I be right in thinking that passing compiler options would set the default char signed-ness? So...the article could suggest passing the -funsigned-char argument to gcc...but maybe I'm wrong.
    Yes, you're right. So... maybe, but I think that's quite unlikely.
    「明後日の夕方には帰ってるからね。」


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