What is string variable?

What is string variable?

A string is a collection of characters. The characters may include alphabets, digits and speacila characters. A variable that is used to store a string is called string variable.

The last character of every string variable is a null character. The null character is denoted by “\0”. This character marks the end of string. Thus when data is entered into a string variable, null character at the end of string will be added automatically. Thus if a string variable is declared with 10 characters, it can store only 9 characters.

Suppose the size of string variable is 12. The value “Pakistan” is assigned to it. The storage of this variable in memory is shown below.

P

A

K

I

S

T

A

N

“\0”

Declaring string variable

Specifying the name of string variable and its length is called declaring string variable. The data type of string variable is char type. The maximum number of characters that a string variable is to store is specified in square brackets in declaration statement.

The syntax to declare a string type variable is:

Char string [len];

Where

                String                    Specifies the name of string variable.

                Len                         Specifies the size or length of string variable. It is an unsigned integer value.

For example, to declare the string variables “name” and  address of length 25 and 35 respectively, the statement is written as:

                Char name[25], address [35]

Initializing string variable

Like other variable, a string variable can also be initialized with a string at the time of its declaration. For example, to declare a string variable ‘str’ and to assign a string “Pakistan” into it, the statement is written as:

Char str [14]       =             “Pakistan”

The string “Pakistan” will be assigned to string variable “str” as show below:

0	1	2	3	4	5	6	7	8	9	10	11	12	13
P	A	K	I	S	T	A	N	\0

A String variable can also be declared and initialized with a string without specifying its length. For example, above statement can be written as:

Char str[]             =             “Pakistan”;

In the above statement, the string variable str is declared and Pakistan is assigned to it. The null character (\0) will be added at the end of the string.

String input and output

The gets() function and scanf() function can be used for input data into a string variable. Mostly, the gets() function is used for this purpose. Similarly, puts() function  and printf() function are used to display the data of string variable on the screen. The format specifier “%s” with formatted input and output function is used for input data into string and to display its data respectively.

For example, to display the contents of ‘str’ variable, the statement is written as;

Printf (“% s’ , str);