STRCAT

Section: Linux Programmer's Manual (3)
Updated: 2008-06-13
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NAME

strcat, strncat - concatenate two strings

SYNOPSIS

#include <string.h>

char *strcat(char *dest, const char *src);

char *strncat(char *dest, const char *src, size_t n);

DESCRIPTION

The strcat() function appends the src string to the dest string, overwriting the null byte (aq\0aq) at the end of dest, and then adds a terminating null byte. The strings may not overlap, and the dest string must have enough space for the result.

The strncat() function is similar, except that

*: it will use at most n characters from src; and
*: src does not need to be null terminated if it contains n or more characters.

As with strcat(), the resulting string in dest is always null terminated.

If src contains n or more characters, strncat() writes n+1 characters to dest (n from src plus the terminating null byte). Therefore, the size of dest must be at least strlen(dest)+n+1.

A simple implementation of strncat() might be:


char*
strncat(char *dest, const char *src, size_t n)
{
    size_t dest_len = strlen(dest);
    size_t i;

    for (i = 0 ; i < n && src[i] != aq\0aq ; i++)
        dest[dest_len + i] = src[i];
    dest[dest_len + i] = aq\0aq;

    return dest;
}

RETURN VALUE

The strcat() and strncat() functions return a pointer to the resulting string dest.

CONFORMING TO

SVr4, 4.3BSD, C89, C99.

COLOPHON

This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.