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).

Interface	Attribute	Value
stpcpy (), strcpy (), strcat ()	Thread safety	MT-Safe

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);
}