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STRDUP(3) Library Functions Manual STRDUP(3)

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

ERRORS

Insufficient memory available to allocate duplicate string.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
strdup (), strndup (), strdupa (), strndupa () Thread safety MT-Safe

STANDARDS

strdup() conforms to SVr4, 4.3BSD, POSIX.1-2001. strndup() conforms to POSIX.1-2008. strdupa() and strndupa() are GNU extensions.

SEE ALSO

alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3), wcsdup(3)

2022-10-09 Linux man-pages 6.01