Suppose we number the bytes in a w-bit word from 0 (least significant) to w/8 - 1 (most significant). Write a code for the following C function, which will return an unsigned value in which byte i of argument x has been replaced by byte b:

unsigned replace_byte (unsigned x, int i, unsigned char b);

Question

Lexi Case

Computers & Technology

12 September, 17:38

Suppose we number the bytes in a w-bit word from 0 (least significant) to w/8 - 1 (most significant). Write a code for the following C function, which will return an unsigned value in which byte i of argument x has been replaced by byte b:

unsigned replace_byte (unsigned x, int i, unsigned char b);

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Answers (1)

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Lucia Sullivan · Answer 1

Answer and Explanation:

/ / header file

#include

/ / function to replace value

unsigned replace_byte (unsigned x, int i, unsigned char b) {

char * p = (char*) (&x);

p[i] = b;

return x;

}

int main () {

/ / declare variables

unsigned n = 0x12345678;

unsigned r1, r2;

/ / display result

printf ("%x/n%x/n", replace_byte (n, 2,0xAB), replace_byte (n, 0,0xAB));

}

output

12ab5678

123456ab

Suppose we number the bytes in a w-bit word from 0 (least significant) to w/8 - 1 (most significant). Write a code for the following C function, which will return an unsigned value in which byte i of argument x has been replaced by byte b:unsigned replace_byte (unsigned x, int i, unsigned char b);