String in C language :

In C language, an array of characters is known as a string. Consider the following example to declare a string :

char st[50]

This statement declares a strings array with 50 characters. The control character '\0' which represents a null character is placed automatically at the end of any string used.

Example :

char name[5] = {'A', 'y', 'a', 'N', '\0'};

String handling functions :

There are four important string handling functions in C Language.

1. strlen() function
2. strcpy() function
3. strcat() function
4. strcmp() function

strlen() function :

strlen() function is used to find the length of a character string.

Syntax :

int n; char st[20]="Bangalore"; n = strlen(st);

This will return length of the string 9 which is assigned to an integer variable n.
Note : That the null character '\0' available at the end of a string is not counted.

strcpy() function :

strcpy() function is used to copy a character variable.

Syntax :

char city[15]; strcpy(city,"BANGALORE")

This will assign the string "BANGALORE" to the character variable city.
Note : That character value like city = "BANGALORE"; cannot be assign in C language.

strcat() function :

strcat() function is used to join character stings. When two character strings are joined, it is referred as concatenation of strings.

Syntax :

char city[20]="BERHAMPORE"; char pin[8]="742103"; strcat(city,pin);

This will join the two strings and store the result in city as "BERHAMPORE742103".
Note : That the resultant string is always stored in the left side string variables.

strcmp() function :

strcmp() function is used to compare two character strings.

Syntax :

char city[20]="MADRAS"; char town[20]="MANGALORE"; strcmp(city,town);

This will return an integer value - 10 which is the difference in the ASCII values of the first mismatching letters 'B' and 'N'.
Note : That the integer value obtained as the difference may be assigned to an integer variable as follows :

int n;
n = strcmp(city,town);

<string.h> :

<string.h> is header in the C standard library for the C language which help us for handling string functions and memory functions.

Example :

/* Description: write a program to use string functions */ #include<stdio.h> #include<strings.h> main() { int n; char name[20],age[20],temp[20],verify[5]="AyaN"; puts("Enter verified user Name : "); gets(name); puts("Enter verified user Age : "); gets(age); n = strlen(name); printf("\nName Length is - %d character.\n",n); strcpy(temp,name); puts(temp); puts("Name Copy Completed.\n"); strcat(name,age); puts(name); puts("Name and age join completed.\n"); if(strcmp(verify,temp)=='\0') { puts(name); puts("This user is verified."); } else { puts(name); puts("This user is not verified."); } getch(); }

Note : gets() use for read strings (Data input) and puts() use for write strings (Data output).

Output :