strncat() — Concatenate Strings
Format
#include <string.h>
char *strncat(char *string1, const char *string2, size_t count);
Language Level
ANSI
Threadsafe
Yes
Description
The strncat()
function
appends the first count characters of string2 to string1 and
ends the resulting string with a null character (\0). If count is
greater than the length of string2, the
length of string2 is used in place of count.
The strncat()
function
operates on null-ended strings. The string argument to the function
should contain a null character (\0) marking the end of the
string.
Return Value
The strncat()
function
returns a pointer to the joined string (string1).
Example
This example demonstrates the difference
between
strcat()
and strncat()
.
The strcat()
function
appends the entire second string to the first, whereas strncat()
appends
only the specified number of characters in the second string to the
first. #include <stdio.h>
#include <string.h>
#define SIZE 40
int main(void)
{
char buffer1[SIZE] = "computer";
char * ptr;
/* Call strcat with buffer1 and " program" */
ptr = strcat( buffer1, " program" );
printf( "strcat : buffer1 = \"%s\"\n", buffer1 );
/* Reset buffer1 to contain just the string "computer" again */
memset( buffer1, '\0', sizeof( buffer1 ));
ptr = strcpy( buffer1, "computer" );
/* Call strncat with buffer1 and " program" */
ptr = strncat( buffer1, " program", 3 );
printf( "strncat: buffer1 = \"%s\"\n", buffer1 );
}
/***************** Output should be similar to: *****************
strcat : buffer1 = "computer program"
strncat: buffer1 = "computer pr"
*/
Related Information
- strcat() — Concatenate Strings
- strncmp() — Compare Strings
- strncpy() — Copy Strings
- strpbrk() — Find Characters in String
- strrchr() — Locate Last Occurrence of Character in String
- strspn() — Find Offset of First Non-matching Character
- wcscat() — Concatenate Wide-Character Strings
- wcsncat() — Concatenate Wide-Character Strings
- <string.h>