15.Character representation in computer memory

 

Character representation in computer memory:

Any piece of data is stored in the computer memory in its binary format.

A character can’t store as it is, in the computer memory.

Every character on the keyboard has its equal binary number.

The decimal equal of binary number is called its ASCII value.

 

Example:

 

 

 

 

 

 

 

 

Example explained:

When a character constant ‘a’ is assigned to the char type of variable ch, then its binary equal 01100001 is stored in the memory. The decimal equal to 01100001 is 97. Here 97 is called ASCII (American Standard Code for Information Interchange) value of ‘a’.

 

Example:

 

 

 

 

 

 

Example explained:

The ASCII value of ‘A’ is 65.

 

Summery:

Whenever a single character constant is assigned to the variable, its binary equal is stored in the memory.

The decimal equal of the binary value is called its ASCII value.

The output of char type of variable is depends on the representation character. %c prints the character and %d prints its equal ASCII value.

 

 

 

Example:

#include<stdio.h>
void main()
{
char ch;
clrscr();
ch=’a’;                              /* Assigns 01100001 */
printf(“%c”,ch);                /* %c prints equal character ‘a’*/
printf(“\n%c”,ch);            /*  %c prints equal number 97*/
}

Output:

a

97

 

Example:

#include<stdio.h>
void main()
{
int n;
clrscr();
n=65;                                 /* Assigns 01000001 */
printf(“%d”,n);                  /* %d prints equal character ‘A’ */
printf(“\n%c”,n);               /* %c prints equal number  65  */
getch();
}

Output:

A

65

 

char:

It is a primary type used to store a single character constant.

It takes 1 byte of memory.

Higher bit is used to store the sign (0 for + and 1 for -)

It can be defined both as signed and unsigned type.

The signed type can store characters, whose ASCII values are in between-128 to 127

The unsigned type can store characters, whose ASCII values are in between 0 to 255.

%c is the representation character of char

 

Example:

#include<stdio.h>
void main()
{
char ch;
clrscr();
printf(“Enter any character:”);
scanf(“%c”,&ch);
printf(“The ASCII value of %c is %c”,ch,ch);
}

Execution:

Enter any character: A

The ASCII value of A is 65

 

Example explained:

Character constant ‘A’ is stored as 01000001.

It is printed with %c as A.

It is printed with %d as 65.

 

Summery of primary data types:

 

Type	size	Range	Rep.characters
int	2bytes	-215 to 215-1	%d
long int	4bytes	-231 to 231-1	%ld
unsigned int	2bytes	0 to 216-1	%u
unsigned long int	4 bytes	0 to 232-1	%lu
float	4bytes	3.4x10-38 to 3.4x1038	%f
double	8bytes	1.7x10-308 to 1.7x10308	%lf
long double	10bytes	3.4x10-4932 to 1.1x104932	%Lf
char	1byte	-128 to 127	%c
unsigned char	1byte	0 to 255	%c