stpcpy, strcpy, strcat - copy or catenate a string
Standard C library (
libc,
-lc)
#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);
stpcpy():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_GNU_SOURCE
-
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;
}
-
stpcpy()
- This function returns a pointer to the terminating null
byte of the copied string.
-
strcpy()
-
strcat() These functions return dst.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
stpcpy (), strcpy (), strcat () |
Thread safety |
MT-Safe |
-
stpcpy()
- POSIX.1-2008.
-
strcpy()
-
strcat() POSIX.1-2001, POSIX.1-2008, C99, 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
#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);
}
strdup(3),
string(3),
wcscpy(3),
string_copying(7)