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| -rw-r--r-- | manual/string.texi | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/manual/string.texi b/manual/string.texi index b91299fd6a..0b667bd3fb 100644 --- a/manual/string.texi +++ b/manual/string.texi @@ -309,12 +309,12 @@ This function was introduced in @w{Amendment 1} to @w{ISO C90}. @end deftypefun @deftypefun size_t strnlen (const char *@var{s}, size_t @var{maxlen}) -@standards{GNU, string.h} +@standards{POSIX.1, string.h} @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} -If the array @var{s} of size @var{maxlen} contains a null byte, -the @code{strnlen} function returns the length of the string @var{s} in -bytes. Otherwise it -returns @var{maxlen}. Therefore this function is equivalent to +This returns the offset of the first null byte in the array @var{s}, +except that it returns @var{maxlen} if the first @var{maxlen} bytes +are all non-null. +Therefore this function is equivalent to @code{(strlen (@var{s}) < @var{maxlen} ? strlen (@var{s}) : @var{maxlen})} but it is more efficient and works even if @var{s} is not null-terminated so @@ -328,7 +328,9 @@ strnlen (string, 5) @result{} 5 @end smallexample -This function is a GNU extension and is declared in @file{string.h}. +This function is part of POSIX.1-2008 and later editions, but was +available in @theglibc{} and other systems as an extension long before +it was standardized. It is declared in @file{string.h}. @end deftypefun @deftypefun size_t wcsnlen (const wchar_t *@var{ws}, size_t @var{maxlen}) @@ -337,7 +339,8 @@ This function is a GNU extension and is declared in @file{string.h}. @code{wcsnlen} is the wide character equivalent to @code{strnlen}. The @var{maxlen} parameter specifies the maximum number of wide characters. -This function is a GNU extension and is declared in @file{wchar.h}. +This function is part of POSIX.1-2008 and later editions, and is +declared in @file{wchar.h}. @end deftypefun @node Copying Strings and Arrays |