Please comment this code. typedef unsigned char BYTE; int main(void) { unsigned

Question

Please comment this code.

typedef unsigned char BYTE;

int main(void)
{
unsigned int addr;
int i,n;
BYTE *ptr;

printf("Address of main function: %x ",(unsigned int) main);
printf("Address of add variable: %x ",(unsigned int) &addr);
printf(" Enter a (hex) address: ");
scanf("%x",&addr);
printf("Enter number of bytes to view: ");
scanf("%d",&n);

printf(" ");
printf(" Address Bytes Characters ");
printf(" ------- ------------------------------ ---------- ");

ptr=(BYTE *)addr;
for(;n>0;n-=10){
printf("%8X ",(unsigned int)ptr);
for(i=0;i<10&&i<n;i++)

printf("%.2X ",*(ptr+i));

for(;i<10;i++)
printf(" ");
for(i=0;i<10&&i<n;i++){
BYTE ch=*(ptr+i);
if(!isprint(ch));
ch='.';
}
printf(" ");
ptr+=10;
}
return 0;
}

Explanation / Answer

here is the commented code..Please note i do not know what the program's objective is..I have commented each and every line as written.

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Program:

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#include<stdio.h>

//here we hava typecased the name of unsigned char as BYTE

typedef unsigned char BYTE;

//start of main function

int main(void)
{

//variables

unsigned int addr;

int i,n;

//this a BYTE pointer

BYTE *ptr;

//print the address of main and variables

printf("Address of main function: %x ",(unsigned int) main);
printf("Address of add variable: %x ",(unsigned int) &addr);

//accept a hex address from the user

printf(" Enter a (hex) address: ");
scanf("%x",&addr);

//ask to user to input the number of bytes to view

printf("Enter number of bytes to view: ");
scanf("%d",&n);

//display a new line

printf(" ");

//display the heading

printf(" Address Bytes Characters ");
printf(" ------- ------------------------------ ---------- ");

//here we have typecased the addr int BYTE pointer

ptr=(BYTE *)addr;
for(;n>0;n-=10){

//display the octal value of ptr pointer

printf("%8X ",(unsigned int)ptr);

//loop for 10 times

for(i=0;i<10&&i<n;i++)

//display the value of *(ptr+i)

printf("%.2X ",*(ptr+i));

//loop for 10 times that display 10 spaces

for(;i<10;i++)

printf(" ");

//loop for 10 times

for(i=0;i<10&&i<n;i++){

//assign ch value of *(ptr+i)

BYTE ch=*(ptr+i);

//if the statement is true assign ch a value '.'

if(!isprint(ch));

ch='.';
}
//print a new line

printf(" ");

//incrment pointer by 10

ptr+=10;

}

return 0;

}

===============================================================

Kindly Check and Verify Thanks..!!!

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