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STPNCPY(3) Linux Programmer's Manual STPNCPY(3)


stpncpy - copy a fixed-size string, returning a pointer to its end


#include <string.h>
char *stpncpy(char *restrict dest, const char *restrict src, size_t n);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):


Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:


The stpncpy() function copies at most n characters from the string pointed to by src, including the terminating null byte ('\0'), to the array pointed to by dest. Exactly n characters are written at dest. If the length strlen(src) is smaller than n, the remaining characters in the array pointed to by dest are filled with null bytes ('\0'), If the length strlen(src) is greater than or equal to n, the string pointed to by dest will not be null-terminated.

The strings may not overlap.

The programmer must ensure that there is room for at least n characters at dest.


stpncpy() returns a pointer to the terminating null byte in dest, or, if dest is not null-terminated, dest+n.


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

Interface Attribute Value
stpncpy () Thread safety MT-Safe


This function was added to POSIX.1-2008. Before that, it was a GNU extension. It first appeared in version 1.07 of the GNU C library in 1993.


strncpy(3), wcpncpy(3)


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