NAME

strcat — concatenate two strings

SYNOPSIS

#include <string.h>

char *strcat(char *restrict s1, const char *restrict s2);


DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

The strcat() function shall append a copy of the string pointed to by s2 (including the terminating NUL character) to the end of the string pointed to by s1. The initial byte of s2 overwrites the NUL character at the end of s1. If copying takes place between objects that overlap, the behavior is undefined.

^[CX] The strcat() function shall not change the setting of errno on valid input.

RETURN VALUE

The strcat() function shall return s1; no return value is reserved to indicate an error.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

This version is aligned with the ISO C standard; this does not affect compatibility with XPG3 applications. Reliable error detection by this function was never guaranteed.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

strncat

XBD <string.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The strcat() prototype is updated for alignment with the ISO/IEC 9899:1999 standard.

Issue 8

Austin Group Defect 448 is applied, adding a requirement that strcat() does not change the setting of errno on valid input.