strncpy() function in C Language

  • strncpy( ) function copies portion of contents of one string into another string. Syntax for strncpy( ) function is given below.
char * strncpy ( char * destination, const char * source, size_t num );
  • Example:
strncpy ( str1, str2, 4) – It copies first 4 characters of str2 into str1.
strncpy ( str2, str1, 4) – It copies first 4 characters of str1 into str2.
  • If destination string length is less than source string, entire source string value won’t be copied into destination string.
  • For example, consider destination string length is 20 and source string length is 30.
  • If you want to copy 25 characters from source string using strncpy( ) function, only 20 characters from source string will be copied into destination string and remaining 5 characters won’t be copied and will be truncated.

Example program for strncpy( ) function in C Language:

    • In this program, only 5 characters from source string “fresh2refresh” is copied into target string using strncpy( ) function.


source string = fresh2refresh
target string =
target string after strncpy( ) = fresh

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.
String functions
1strcat ( ) Concatenates str2 at the end of str1.
2strncat ( ) appends a portion of string to another
3strcpy ( ) Copies str2 into str1
4strncpy.(.) copies given number of characters of one string to another
5strlen ( ) gives the length of str1.
6strcmp ( ) Returns 0 if str1 is same as str2. Returns <0 if strl < str2. Returns >0 if str1 > str2.
7strcmpi ( ) Same as strcmp() function. But, this function negotiates case.  “A” and “a” are treated as same.
8strchr ( ) Returns pointer to first occurrence of char in str1.
9strrchr ( ) last occurrence of given character in a string is found
10strstr ( ) Returns pointer to first occurrence of str2 in str1.
11strrstr ( ) Returns pointer to last occurrence of str2 in str1.
12strdup ( ) duplicates the string
13strlwr ( ) converts string to lowercase
14strupr ( ) converts string to uppercase
15strrev ( ) reverses the given string
16strset ( ) sets all character in a string to given character
17strnset ( ) It sets the portion of characters in a string to given character
18strtok ( ) tokenizing given string using delimiter appreciates your contribution please mail us the questions you have to so that it will be useful to our job search community

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