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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | CAVEATS | EXAMPLES | SEE ALSO | COLOPHON |
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strcpy(3) Library Functions Manual strcpy(3)
strcpy, strcat - copy or catenate a string
Standard C library (libc, -lc)
#include <string.h>
char *strcpy(char *restrict dst, const char *restrict src);
char *strcat(char *restrict dst, const char *restrict src);
strcpy()
This function copies 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.
It is equivalent to
stpcpy(dst, src), dst
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.
It is equivalent to
stpcpy(strnul(dst), src), dst
These functions return dst.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ strcpy(), strcat() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
C11, POSIX.1-2008.
POSIX.1-2001, C89, SVr4, 4.3BSD.
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
⟨https://www.joelonsoftware.com/2001/12/11/back-to-basics/⟩.
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(void)
{
char *buf1;
size_t len, size;
size = strlen("Hello ") + strlen("world") + strlen("!") + 1;
buf1 = malloc(sizeof(*buf1) * size);
if (buf1 == NULL)
err(EXIT_FAILURE, "malloc()");
strcpy(buf1, "Hello ");
strcat(buf1, "world");
strcat(buf1, "!");
len = strlen(buf1);
printf("[len = %zu]: ", len);
puts(buf1); // "Hello world!"
free(buf1);
exit(EXIT_SUCCESS);
}
stpcpy(3), strdup(3), string(3), wcscpy(3), string_copying(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.18.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2026-05-24. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.18 2026-02-25 strcpy(3)
Pages that refer to this page: bcopy(3), memccpy(3), memcpy(3), memmove(3), stpcpy(3), string(3), wcpcpy(3), wcscat(3), wcscpy(3), feature_test_macros(7), signal-safety(7), string_copying(7)
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HTML rendering created 2026-05-24 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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