welibc
A clear, secure, and well documented standard C library
strncat.c
Go to the documentation of this file.
1 /*******************************************************************************
2  Copyright (c) 2018 Walt Elam
3  All rights reserved.
4 
5  Redistribution and use in source and binary forms, with or without
6  modification, are permitted provided that the following conditions are met:
7 
8  1. Redistributions of source code must retain the above copyright notice,
9  this list of conditions and the following disclaimer.
10 
11  2. Redistributions in binary form must reproduce the above copyright
12  notice, this list of conditions and the following disclaimer in the
13  documentation and/or other materials provided with the distribution.
14 
15  3. Neither the name of the copyright holder nor the names of its
16  contributors may be used to endorse or promote products derived from
17  this software without specific prior written permission.
18 
19  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
23  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  POSSIBILITY OF SUCH DAMAGE.
30 *******************************************************************************/
31 /***************************************************************************//**
32  @file strncat.c
33 
34  @brief Defines the strncat function
35 *******************************************************************************/
36 #include <string.h>
37 
38 /*******************************************************************************
39  strncat
40 *//**
41  @brief Concatenates two strings, appending no more than n characters
42  @param *s1 Destination string
43  @param *s2 String to be appended
44  @param n Maximum number of characters to append
45 
46  The strncat function appends not more than n characters (a null character
47  and characters that follow it are not appended) from the array pointed to by
48  s2 to the end of the string pointed to by s1. The initial character of s2
49  overwrites the null character at the end of s1. A terminating null character
50  is always appended to the result. If copying takes place between objects
51  that overlap, the behavior is undefined.
52 
53  @note The maximum number of characters that can end up in the array
54  pointed to be s1 is strlen(s1)+n+1.
55 
56  @note Copying between overlapping objects is supported, but the source may
57  be overwritten.
58 
59  @return The value of s1
60 *******************************************************************************/
61 char *
62 strncat(char *s1, const char *s2, size_t n)
63 {
64  size_t len1 = 0;
65  size_t len2 = 0;
66 
67  if (!s1 || !s2)
68  {
69  return s1;
70  }
71 
72  len1 = strlen(s1);
73  len2 = strlen(s2);
74 
75  if (len2 < n)
76  {
77  n = len2;
78  }
79 
80  memmove(s1 + len1, s2, n);
81  s1[len1 + n] = '\0';
82 
83  return s1;
84 }
85 
strlen
size_t strlen(const char *s)
Computes the length of a string.
Definition: strlen.c:51
string.h
Declares types, functions, and macros for manipulating arrays of character type and other objects tre...
memmove
void * memmove(void *s1, const void *s2, size_t n)
Copies n characters from s2 into s1.
Definition: memmove.c:59
strncat
char * strncat(char *s1, const char *s2, size_t n)
Concatenates two strings, appending no more than n characters.
Definition: strncat.c:62
Generated on Fri Sep 3 2021 12:24:21 for welibc by   doxygen 1.8.17