strdup(3) - v6.14 | Better Man Pages

Library Functions Manual

NAME

strdup, strndup, strdupa, strndupa - duplicate a string

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#include <string.h>

char *strdup(const char *s);

char *strndup(size_t n;
              const char s[n], size_t n);
char *strdupa(const char *s);
char *strndupa(size_t n;
              const char s[n], size_t n);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

strdup():



    _XOPEN_SOURCE >= 500

        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L

        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

strndup():



    Since glibc 2.10:

        _POSIX_C_SOURCE >= 200809L

    Before glibc 2.10:

        _GNU_SOURCE

strdupa(), strndupa():



    _GNU_SOURCE

DESCRIPTION

The strdup() function returns a pointer to a new string which is a duplicate of the string s. Memory for the new string is obtained with malloc(3), and can be freed with free(3).

The strndup() function is similar, but copies at most n bytes. If s is longer than n, only n bytes are copied, and a terminating null byte ('\0') is added.

strdupa() and strndupa() are similar, but use alloca(3) to allocate the buffer.

RETURN VALUE

On success, the strdup() function returns a pointer to the duplicated string. It returns NULL if insufficient memory was available, with errno set to indicate the error.