strdup

 

C

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Type support

Program utilities

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Dynamic memory management

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Atomic operations (C11)

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Technical Specifications

 

Technical Specifications

Extensions for embedded processors

Dynamic memory extensions

Floating-point extensions part 1: Binary floating-point

Floating-point extensions part 4: Supplementary functions

 

Dynamic memory extensions

fmemopen

open_memstreamopen_wmemstream

asprintfaswprintfvasprintfvaswprintf

getlinegetwlinegetdelimgetwdelim

strdup

strndup

 

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

Run this code

#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

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