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strcpy(3) — Linux manual page

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

strcpy(3)                Library Functions Manualstrcpy(3)

NAME top

       stpcpy, strcpy, strcat - copy or catenate a string

LIBRARY top

       Standard C library (libc,-lc)

SYNOPSIS top

#include <string.h>char *stpcpy(char *restrictdst, const char *restrictsrc);char *strcpy(char *restrictdst, const char *restrictsrc);char *strcat(char *restrictdst, const char *restrictsrc);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):stpcpy():           Since glibc 2.10:               _POSIX_C_SOURCE >= 200809L           Before glibc 2.10:               _GNU_SOURCE

DESCRIPTION top

stpcpy()strcpy()              These functions copy the string pointed to bysrc, into a              string at the buffer pointed to bydst.  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 bysrc, after              the string pointed to bydst (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 top

stpcpy()              This function returns a pointer to the terminating null              byte of the copied string.strcpy()strcat()              These functions returndst.

ATTRIBUTES top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │stpcpy(),strcpy(),strcat()         │ Thread safety │ MT-Safe │       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

stpcpy()              POSIX.1-2008.strcpy()strcat()              C11, POSIX.1-2008.

STANDARDS top

stpcpy()              POSIX.1-2008.strcpy()strcat()              POSIX.1-2001, C89, SVr4, 4.3BSD.

CAVEATS top

       The stringssrc anddst may not overlap.       If the destination buffer is not large enough, the behavior is       undefined.  See_FORTIFY_SOURCEinfeature_test_macros(7).strcat() can be very inefficient.  Read about Shlemiel the painter       ⟨https://www.joelonsoftware.com/2001/12/11/back-to-basics/⟩.

EXAMPLES top

       #include <err.h>       #include <stdio.h>       #include <stdlib.h>       #include <string.h>       int       main(void)       {           char    *p;           char    *buf1;           char    *buf2;           size_t  len, size;           size = strlen("Hello ") + strlen("world") + strlen("!") + 1;           buf1 = malloc(sizeof(*buf1) * size);           if (buf1 == NULL)               err(EXIT_FAILURE, "malloc()");           buf2 = malloc(sizeof(*buf2) * size);           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);       }

COLOPHON top

       This page is part of theman-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-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  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 isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17strcpy(3)

Pages that refer to this page:bcopy(3), memccpy(3), memcpy(3), memmove(3), string(3), wcpcpy(3), wcscat(3), wcscpy(3), feature_test_macros(7), signal-safety(7), string_copying(7)