strdup

 

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoiatolatoll (C99) strtolstrtoll (C99)	strtoulstrtoull (C99) strtofstrtodstrtold (C99)(C99) strtoimaxstrtoumax (C99)(C99)
String manipulation
strcpystrcpy_s (C11)
strncpystrncpy_s (C11)
strcatstrcat_s (C11)
strncatstrncat_s (C11)
strxfrm
strdup (C23)
strndup (C23)
String examination
strlenstrnlen_s (C11) strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtokstrtok_s (C11)
Memory manipulation
memchr
memcmp
memsetmemset_s (C11)
memcpymemcpy_s (C11)
memmovememmove_s (C11)
memccpy (C23)
Miscellaneous
strerrorstrerror_sstrerrorlen_s (C11)(C11)

 

Defined in header <string.h>
char *strdup( const char *str1 );		(since C23)

Returns a pointer to a null-terminated byte string, which is a duplicate of the string pointed to by str1. The space for the new string is obtained as if the malloc was invoked. The returned pointer must be passed to free to avoid a memory leak.

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

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

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
 
int main(void)
{
    const char *s1 = "Duplicate me!";
    char *s2 = strdup(s1);
    printf("s2 = \"%s\"\n", s2);
    free(s2);
}

Output:

s2 = "Duplicate me!"

See also

strndup (C23)	allocates a copy of a string of specified size (function)
strcpystrcpy_s (C11)	copies one string to another (function)
malloc	allocates memory (function)
free	deallocates previously allocated memory (function)