strlen() function in C Language

• strlen( ) function in C gives the length of the given string. Syntax for strlen( ) function is given below.

size_t strlen ( const char * str );

• strlen( ) function counts the number of characters in a given string and returns the integer value.
• It stops counting the character when null character is found. Because, null character indicates the end of the string in C.

Example program for strlen() function in C language:

• In below example program, length of the string “fresh2refres.com” is determined by strlen( ) function as below. Length of this string 17 is displayed as output.

C

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#include <stdio.h> #include <string.h>   int main( ) {     int len;     char array[20]="fresh2refresh.com" ;       len = strlen(array) ;       printf ( "\string length  = %d \n" , len ) ;     return 0; }

Output:

string length = 17

Other String functions in C Language:

• String.h header file supports all the string functions in C language. All the string functions are given below.

S.no	String functions	Description
1	strcat ( )	Concatenates str2 at the end of str1.
2	strncat ( )	appends a portion of string to another
3	strcpy ( )	Copies str2 into str1
4	strncpy ( )	copies given number of characters of one string to another
5	strlen ( )	gives the length of str1.
6	strcmp ( )	Returns 0 if str1 is same as str2. Returns <0 if strl < str2. Returns >0 if str1 > str2.
7	strcmpi ( )	Same as strcmp() function. But, this function negotiates case.  “A” and “a” are treated as same.
8	strchr ( )	Returns pointer to first occurrence of char in str1.
9	strrchr ( )	last occurrence of given character in a string is found
10	strstr ( )	Returns pointer to first occurrence of str2 in str1.
11	strrstr ( )	Returns pointer to last occurrence of str2 in str1.
12	strdup ( )	duplicates the string
13	strlwr ( )	converts string to lowercase
14	strupr ( )	converts string to uppercase
15	strrev ( )	reverses the given string
16	strset ( )	sets all character in a string to given character
17	strnset ( )	It sets the portion of characters in a string to given character
18	strtok ( )	tokenizing given string using delimiter

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