strdup

< c‎ | experimental‎ | dynamic
Defined in header <string.h>
char * strdup( const char *str1 );
 (dynamic memory TR)

Returns a pointer to a null-terminated byte string, which is a duplicate of the string pointed to by str1. The returned pointer must be passed to free to avoid a memory leak.

If an error occurs, a null pointer is returned and errno may be set.

As all functions from Dynamic Memory TR, strdup is only guaranteed to be available if __STDC_ALLOC_LIB__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT2__ to the integer constant 1 before including string.h.

Parameters

str1 - pointer to the null-terminated byte string to duplicate

Return value

A pointer to the newly allocated string, or a null pointer if an error occurred.

Notes

The function is identical to the POSIX strdup.

Example

#ifdef __STDC_ALLOC_LIB__
#define __STDC_WANT_LIB_EXT2__ 1
#else
#define _POSIX_C_SOURCE 200809L
#endif
 
#include <string.h>
#include <assert.h>
#include <stdlib.h>
 
int main(void)
{
    const char *s1 = "String";
    char *s2 = strdup(s1);
    assert(strcmp(s1, s2) == 0);
    free(s2);
}

See also

(dynamic memory TR)
 allocate a copy of a string up to specified size
(function)
(C11)
 copies one string to another
(function)
allocates memory
(function)