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Converts a character to lowercase.
Syntax
int tolower(
   int c
);
int _tolower(
   int c
);
int towlower(
   wint_t c
);
int _tolower_l(
   int c,
   _locale_t locale
);
int _towlower_l(
   wint_t c,
   _locale_t locale
);
Parameters
c
Character to convert.
locale
Locale to use for locale-specific translation.
Return value
Each of these routines converts a copy of c to lower case if the conversion is possible, and returns the result. There's no return value reserved to indicate an error.
Remarks
Each of these routines converts a given uppercase letter to a lowercase letter if it's possible and relevant. The case conversion of towlower is locale-specific. Only the characters relevant to the current locale are changed in case. The functions without the _l suffix use the currently set locale. The versions of these functions that have the _l suffix take the locale as a parameter and use that instead of the currently set locale. For more information, see Locale.
In order for _tolower to give the expected results, __isascii and isupper must both return nonzero.
By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.
Generic-text routine mappings
| TCHAR.H routine | _UNICODE and _MBCS not defined | 
_MBCS defined | 
_UNICODE defined | 
|---|---|---|---|
_totlower | 
tolower | 
_mbctolower | 
towlower | 
_totlower_l | 
_tolower_l | 
_mbctolower_l | 
_towlower_l | 
Note
_tolower_l and _towlower_l have no locale dependence and are not meant to be called directly. They are provided for internal use by _totlower_l.
Requirements
| Routine | Required header | 
|---|---|
tolower | 
<ctype.h> | 
_tolower | 
<ctype.h> | 
towlower | 
<ctype.h> or <wchar.h> | 
For more compatibility information, see Compatibility.
Example
See the example in to functions.
See also
Data conversion
is, isw routines
to functions
Locale
Interpretation of multibyte-character sequences