strncat() function in C Language

  • strncat( ) function in C language concatenates ( appends ) portion of one string at the end of another string. 
  • Syntax for strncat( ) function is given below.
char * strncat ( char * destination, const char * source, size_t num );
  • Example :
strncat ( str2, str1, 3 ); – First 3 characters of str1 is concatenated at the end of str2.
strncat ( str1, str2, 3 ); - First 3 characters of str2 is concatenated at the end of str1.
  • As you know, each string in C is ended up with null character (‘\0′).
  • In strncat( ) operation, null character of destination string is overwritten by source string’s first character and null character is added at the end of new destination string which is created after strncat( ) operation.

Example program for strncat( ) function in C Language:

    • In this program, first 5 characters of the string “fresh2refresh” is concatenated at the end of the string ”C tutorial” using strncat( ) function and result is displayed as “C tutorial fres”.


Source string                       = fresh2refresh
Target string                        = C tutorial
Target string after strcat( ) = C tutorial fres

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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