strdup - Man Page

duplicate a string

Library

Standard C library (libc, -lc)

Synopsis

#include <string.h>

char *strdup(const char *s);

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