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What is strlen function in C language?
The C library function size_t strlen(const char *str) computes the length of the string str up to, but not including the terminating null character.
An array of characters is called a string.
Declaration
Given below is the declaration of an array −
char stringname [size];
For example − char a[50]; string of length 50 characters
Initialization
- Using single character constant −
char a[10] = { ‘H’, ‘e’, ‘l’, ‘l’, ‘o’ ,‘\0’}- Using string constants −
char a[10] = "Hello":;
Accessing − There is a control string "%s" used for accessing the string till it encounters ‘\0’
The strlen ( ) function
This function gives the length of the string, i.e., the number of characters in a string.
Syntax
The syntax of strlen() function is as follows −
int strlen (string name)
Sample program
The following program shows the usage of strlen() function.
#include <string.h>
main ( ){
char a[30] = "Hello";
int l;
l = strlen (a);
printf ("length of the string = %d", l);
getch ( );
}Output
When the above program is executed, it produces the following result −
length of the string = 5 Note : "\0" not counted as a character.
Consider another example.
Example
Following is the C program to find the length of a string −
#include<stdio.h>
#include<string.h>
int main(){
int str1, str2;
//initializing the strings
char string1[] = "Welcome To";
char string2[] = {'T','U','T','O','R','I','A','L','\0'};
//calculating the length of the two strings
str1 = strlen(string1);
str2 = strlen(string2);
printf("string1 length is: %d
", str1);
printf("string2 length is: %d
", str2);
}Output
When the above program is executed, it produces the following result −
string1 length is: 10 string2 length is: 8
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