BITWISE opearation

[Shah Satish]

Hello.. I want to do NOT operation..but i here output is wrong.. main() { unsigned int Value=4; /* 4 = 0000 0100 */ Value = ~ Value; /* 251 = 1111 1011 */ } but my output is 4294967291 insted of 251. Please help me out.. Thanks Shah

[JudyL_MD]

If you only want to use 8 bits, you need to use unsigned char. Int is 32 bit longs, so you get FFFFFFFB when you do the NOT operation. udy

[CPallini]

Actually The output (4294967291 = 0xFFFFFFFB) is correct (your assumptions are wrong) because the unsigned int type is 4-bytes wide:

HEX: ~0x00000004 =
0xFFFFFFFB

BINARY: ~0000 0000 0000 0000 0000 0000 0000 0100 =
1111 1111 1111 1111 1111 1111 1111 1011

if you want to obtain 251 then use the unsigned char type:

unsigned char Value;
Value = 4;
Value = ~ Value;

:)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.

[David Crow]

Shah Satish wrote:

unsigned int Value=4; /* 4 = 0000 0100 */

Actually:

unsigned int Value = 4; /* 4 = 0000 0000 0000 0000 0000 0000 0000 0100 */
Value = ~Value; /* 4294967291 = 1111 1111 1111 1111 1111 1111 1111 1011 */

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"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

[Cedric Moonen]

Shah Satish wrote:

/* 4 = 0000 0100 */

This is wrong. An integer is coded on 4 bytes, not on 1 byte, so it is 00000000 00000000 00000000 00000100 instead. Try to invert it, and you'll see that you will get 4294967291. Replace the unsigned int by an unsigned char if you want to work on 1 byte.

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Cédric Moonen Software developer
Charting control [v1.2]

[apoorva_raje]

not very sure abt this.. bt i guess that if u wanna arrive at 251 ie. -5 (sign extended), u gotta use short int or int instead of unsigned int. hope this helps

[Rajkumar R]

Hi, You are using unsigned int it is 32 bits long for 32 bit processer, and or depending on your compiler. hence ~value is 0xFFFFFFFB not 0x000000FB, if you really want 8bits of data use unsigned char instead. Best Regards Raj