Chapter 2, Problem 2.60HW

Explanation of Solution

Function definition for “replace_byte()” function:

The implementation for “replace_byte()” function is given below:

//Header file

#include <stdio.h>

#include <assert.h>

//Function definition for replace byte function

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

{

//Check if value of "i" is less than "0", then

if (i < 0)

{

//Display error message

printf("error: value of i is negetive\n");

return x;

}

/* Check if value of "i" is greater than "sizeof(unsigned)-1", then */

if (i > sizeof(unsigned)-1)

{

//Display error message

printf("error: value of i is too high");

return x;

}

/* Assign the value of mask that is for byte

in general, 1 bye = 8 bits and then << implies *8 */

unsigned m = ((unsigned) 0xFF) << (i << 3);

//Defines the byte position

unsigned bytePosition = ((unsigned) b) << (i << 3);

//Return given value

return (x & ~m) | bytePosition;

}

//Main function

int main(int argc, char *argv[])

{

/* Call replace_byte function for replace byte 2 in given "x" by byte "0xAB" */

unsigned replaceByte2  = replace_byte(0x12345678, 2, 0xAB);

/* Call replace_byte function for replace byte 0 in given "x" by byte "0xAB" */

unsigned replaceByte0 = replace_byte(0x12345678, 0, 0xAB);

/* Check if the replaced byte equals to given value using "assert" function */

assert(replaceByte2  == 0x12AB5678);

assert(replaceByte0  == 0x123456AB);

return 0;

}

The given code is used to return an unsigned value in which byte “i” of argument “x” has been replaced by “b”...