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Manual

strcpy

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ATTRIBUTES
STANDARDS
STANDARDS
CAVEATS
EXAMPLES
SEE ALSO

NAME

stpcpy, strcpy, strcat - copy or catenate a string

LIBRARY

Standard C library ( libc , -lc )

SYNOPSIS

#include <string.h>

char *stpcpy(char *restrict dst , const char *restrict src );
char *strcpy(char *restrict dst , const char *restrict src );
char *strcat(char *restrict dst , const char *restrict src );

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

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

DESCRIPTION

stpcpy ()
strcpy ()

These functions copy the string pointed to by src , into a string at the buffer pointed to by dst . The programmer is responsible for allocating a destination buffer large enough, that is, strlen(src) + 1 . For the difference between the two functions, see RETURN VALUE.

strcat ()

This function catenates the string pointed to by src , after the string pointed to by dst (overwriting its terminating null byte). The programmer is responsible for allocating a destination buffer large enough, that is, strlen(dst) + strlen(src) + 1 .

An implementation of these functions might be:

char *
stpcpy(char *restrict dst, const char *restrict src)
{
char *p;
p = mempcpy(dst, src, strlen(src));
*p = '\0';
return p;
}
char *
strcpy(char *restrict dst, const char *restrict src)
{
stpcpy(dst, src);
return dst;
}
char *
strcat(char *restrict dst, const char *restrict src)
{
stpcpy(dst + strlen(dst), src);
return dst;
}

RETURN VALUE

stpcpy ()

This function returns a pointer to the terminating null byte of the copied string.

strcpy ()
strcat ()

These functions return dst .

ATTRIBUTES

For an explanation of the terms used in this section, see attributes (7).

Image grohtml-463342-1.png

STANDARDS

stpcpy ()

POSIX.1-2008.

strcpy ()
strcat ()

C11, POSIX.1-2008.

STANDARDS

stpcpy ()

POSIX.1-2008.

strcpy ()
strcat ()

POSIX.1-2001, C89, SVr4, 4.3BSD.

CAVEATS

The strings src and dst may not overlap.

If the destination buffer is not large enough, the behavior is undefined. See _FORTIFY_SOURCE in feature_test_macros (7).

strcat () can be very inefficient. Read about Shlemiel the painter .

EXAMPLES

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(void)
{
char *p;
char *buf1;
char *buf2;
size_t len, maxsize;
maxsize = strlen("Hello ") + strlen("world") + strlen("!") + 1;
buf1 = malloc(sizeof(*buf1) * maxsize);
if (buf1 == NULL)
err(EXIT_FAILURE, "malloc()");
buf2 = malloc(sizeof(*buf2) * maxsize);
if (buf2 == NULL)
err(EXIT_FAILURE, "malloc()");
p = buf1;
p = stpcpy(p, "Hello ");
p = stpcpy(p, "world");
p = stpcpy(p, "!");
len = p - buf1;
printf("[len = %zu]: ", len);
puts(buf1); // "Hello world!"
free(buf1);
strcpy(buf2, "Hello ");
strcat(buf2, "world");
strcat(buf2, "!");
len = strlen(buf2);
printf("[len = %zu]: ", len);
puts(buf2); // "Hello world!"
free(buf2);
exit(EXIT_SUCCESS);
}