The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
A newer edition of this document exists here


strcpy - copy a string


#include <string.h>

char *strcpy(char *restrict
s1, const char *restrict s2);


[CX] [Option Start] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

The strcpy() function shall copy the string pointed to by s2 (including the terminating null byte) into the array pointed to by s1. If copying takes place between objects that overlap, the behavior is undefined.


The strcpy() function shall return s1; no return value is reserved to indicate an error.


No errors are defined.

The following sections are informative.


Initializing a String

The following example copies the string "----------" into the permstring variable.

#include <string.h>
static char permstring[11];
strcpy(permstring, "----------");

Storing a Key and Data

The following example allocates space for a key using malloc() then uses strcpy() to place the key there. Then it allocates space for data using malloc(), and uses strcpy() to place data there. (The user-defined function dbfree() frees memory previously allocated to an array of type struct element *.)

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
/* Structure used to read data and store it. */
struct element {
    char *key;
    char *data;

struct element *tbl, *curtbl; char *key, *data; int count; ... void dbfree(struct element *, int); ... if ((curtbl->key = malloc(strlen(key) + 1)) == NULL) { perror("malloc"); dbfree(tbl, count); return NULL; } strcpy(curtbl->key, key);
if ((curtbl->data = malloc(strlen(data) + 1)) == NULL) { perror("malloc"); free(curtbl->key); dbfree(tbl, count); return NULL; } strcpy(curtbl->data, data); ...


Character movement is performed differently in different implementations. Thus, overlapping moves may yield surprises.

This issue is aligned with the ISO C standard; this does not affect compatibility with XPG3 applications. Reliable error detection by this function was never guaranteed.






strncpy(), the Base Definitions volume of IEEE Std 1003.1-2001, <string.h>


First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The strcpy() prototype is updated for alignment with the ISO/IEC 9899:1999 standard.

End of informative text.

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