strndup(3) — Linux manual page

strndup(3)               Library Functions Manual              strndup(3)

NAME         top

       strndup - nonstring duplicate-into-string

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <string.h>  // see memory.h(3head)

       char *strndup(size_t n;
                     const char strn[n], size_t n);

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

       strndup():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION         top

       This function duplicates at most n nonnull characters from the
       array pointed to by strn, followed by a null character, into new
       memory obtained with malloc(3).

RETURN VALUE         top

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

ERRORS         top

       See malloc(3).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ strndup()                            │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       POSIX.1-2008.

SEE ALSO         top

       memory.h(3head), malloc(3), strndupa(3)

COLOPHON         top

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Linux man-pages 6.19            2026-08-17                     strndup(3)

Pages that refer to this page: memory.h(3head),  strndupa(3),  string_copying(7)

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