Thread: Decimal, Octal & Hexadecimal

  1. #1
    Registered User
    Join Date
    Mar 2011

    Question Decimal, Octal & Hexadecimal

    Hi all.

    Can anyone help me clarify these statements.

    1. C support unary minus operator for hexadecimal and octal literals (eg. -0xFF, -002)
    2. Negative hexadecimal will count from FFFFFFFF for 'int' type.?
    3. Negative octal will count from 377777777777 for 'int' type. ?

    Am I right?

    I just try this out.

    #include <stdio.h>
    int main()
    	int x = -1;
    	printf("%i %o %x\n", x, x, x);
    	int y = -0x01;
    	printf("%i %o %x\n", y, y, y);
    	int z = -001;
    	printf("%i %o %x\n", z, z, z);
    	return 0;	
    Output :
    1 377777777777 FFFFFFFF
    1 377777777777 FFFFFFFF
    1 377777777777 FFFFFFFF

    Lastly, how to print hexadecimal and octal as '-0x01' and '-001' instead of 'FFFFFFFF' and '377777777777' using printf?



  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    You would need to do something like
    if ( x < 0 ) {
      x = -x;
    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.

  3. #3
    Registered User
    Join Date
    Sep 2008
    Toronto, Canada
    I think it's 37777777777 (10 x '7', not 11 x '7').

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