C – strlen() function

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  • 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:

  • 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.
#include <stdio.h>
#include <string.h>

int main( )
{
    int len;
    char array[20]="cprogramming.mynetworkip.com" ;

    len = strlen(array) ;

    printf ( "string length  = %d n" , len ) ;
    return 0;
}

Output:

string length = 17

Other C String functions:

    • String.h header file supports all the string functions in C language. All the string functions are given below.
    • Click on each string function name below to display example programs.
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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