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strcpy

Section: C Library Functions (3)
Updated: 202-0-03
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NAME

strcpy, strcat - string copy/catenate

LIBRARY

Standard C library (libc,~-lc)

SYNOPSIS

#include <string.h>
char *strcpy(char *restrict dst, const char *restrict src);
char *strcat(char *restrict dst, const char *restrict src);

DESCRIPTION

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

RETURN VALUE

These functions return dst.

ATTRIBUTES

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

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

STANDARDS

C11, POSIX.-2008.

HISTORY

POSIX.-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).

EXAMPLES

#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); }