strncpy function(Bounded String Copy) in C Language – example and detail

In the C Programming Language, the strncpy characteristic copies the first n characters of the array pointed to through s2 into the array pointed to through s1. It returns a pointer to the destination.

If the strncpy function encounters a null personality in s2, the function will add null characters to s1 till n characters have been written.


The syntax for the strncpy characteristic in the C Language is:

char *strncpy(char *s1, const char *s2, size_t n);

Parameters or Arguments

s1 An array where s2 will be copied to. s2 The string to be copied. n The range of characters to copy.


The strncpy function returns s1.

Required Header

In the C Language, the required header for the strncpy function is:

#include <string.h>

Applies To

In the C Language, the strncpy function can be used in the following versions:

ANSI/ISO 9899-1990

strncpy Example

Let’s appear at an instance to see how you would use the strncpy function in a C program:

/* Example using strncpy by */

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

int main(int argc, const char * argv[])
    /* Create an example variable capable of holding 50 characters */
    char example[50];

    /* Copy 16 characters into the example variable
     from the string " knows strncpy" */
    strncpy (example, " knows strncpy!", 16);

    /* Add the required NULL to terminate the copied string */
    /* strncpy does not do this for you! */
    example[16] = '\0';

    /* Display the contents of the example variable to the screen */
    printf("%s\n", example);

    return 0;

When compiled and run, this utility will output:

Similar Functions

Other C functions that are comparable to the strncpy function:

memcpy feature memmove characteristic strcpy characteristic