STRNCPY(3) Library Functions Manual STRNCPY(3)

strncpy — copy part of a string

#include <string.h>

char *strncpy(char *restrict s1, const char *restrict s2, size_t n);

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 IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.

The strncpy () function shall copy not more than n bytes (bytes that follow a null byte are not copied) from the array pointed to by s2 to the array pointed to by s1. If copying takes place between objects that overlap, the behavior is undefined.

If the array pointed to by s2 is a string that is shorter than n bytes, null bytes shall be appended to the copy in the array pointed to by s1, until n bytes in all are written.

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

No errors are defined.

None.

Character movement is performed differently in different implementations. Thus, overlapping moves may yield surprises.

If there is no null byte in the first n bytes of the array pointed to by s2, the result is not null-terminated.

None.

None.

strcpy(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <string.h>

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

The strncpy () prototype is updated for alignment with the ISO/IEC 9899:1999 (“ISO C99”) standard.

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December 6, 2001 posix.fail