Question

2. Write a C code with a function to swap the first four bits of an 8-bit unsigned number with the last four bits. The main function should include the variable declaration and initialisation using the appropriate data type, the function call and the display of the result in hexadecimal. The parameter(s) should be passed to the function by reference.

Answer 1

The following C code gives you the required functionality:

#include<stdio.h>
void swap(int *n);

int main()
{
unsigned char x;
printf("Enter the value: ");
scanf("%u",&x);
swap(&x);
return 0;
}//end of main function

void swap(int *n)
{
unsigned char d = *n;
char s[6] = {'A', 'B', 'C', 'D', 'E', 'F'};
char hex[2];
int j=1,res,i;
for(i=0;i<2;i++)
hex[i]='0';

//converting into hexadecimal values
while(d!=0)
{
res = d%16;
if(res<=9)
hex[j--]=res;
else
hex[j--]=s[res-10];
d=d/16;
}
printf("Before Swapping: 0x");
for(i=0;i<2;i++)
printf("%c",hex[i]);
printf("\n");
char t;
t = hex[0];
hex[0]=hex[1];
hex[1]=t;
printf("After Swapping: 0x");
for(i=0;i<2;i++)
printf("%c",hex[i]);

}//end of swap function

Output:

Enter the value: 12 Before Swapping: exec After Swapping: exce Process returned (8x0) execution time : 1.703 s Press any key to continue.