Determine columns needed for a fixed-size wide-character string
#define _XOPEN_SOURCE /* See feature_test_macros(7) */ #include <wchar.h> int wcswidth(const wchar_t *s, size_t n);
The wcswidth() function returns the number of columns needed to represent the wide-character string pointed to by s, but at most n wide characters. If a nonprintable wide character occurs among these characters, -1 is returned.
The wcswidth() function returns the number of column positions for the wide-character string s, truncated to at most length n.
The wcswidth() function is thread-safe with exceptions. It can be safely used in multithreaded applications, as long as setlocale(3) is not called to change the locale during its execution.
POSIX.1-2001.
The behavior of wcswidth() depends on the LC_CTYPE category of the current locale.
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