Question

Write a C function that declares a static integer array, M, and implements fetch and store operations that use shift and Boolean operations to access individual bytes.

Answer 1

C program for accessing and storing static integer byte by byte:

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#include<stdio.h>
static int arr[5]={0xabcd,2,3,4,5};
void main(){
int *p=&arr;
int mask=0x000f;
printf("Accessing arr[0] byte by byte:\n");
printf("mask byte\n");
printf("%x ",mask);
printf("%x\n",(*p)&mask);
mask=mask<<4; // mask= 0x00f0 for accessing LSByte
printf("%x ",mask);
printf("%x\n",((*p)&mask)>>4);
mask=mask<<4; // mask= 0x0f00
printf("%x ",mask);
printf("%x\n",((*p)&mask)>>8);
mask=mask<<4; // mask= 0xf000 for accessing MSByte
printf("%x ",mask);
printf("%x\n",((*p)&mask)>>12);

printf("array element at arr[%d]: %x\n",0,arr[0]);
int dataByte=0xe;
*p=(*p)|(dataByte<<4); // for storing data byte at location 3 in first element of arrray
printf("aftering storing data byte arr[%d]= %x\n",0,arr[0]);

}

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