1TOLOWER(3P) POSIX Programmer's Manual TOLOWER(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 tolower, tolower_l — transliterate uppercase characters to lowercase
13
15 #include <ctype.h>
16 int tolower(int c);
18 int tolower_l(int c, locale_t locale);
19
21 For tolower(): The functionality described on this reference page is
22 aligned with the ISO C standard. Any conflict between the requirements
23 described here and the ISO C standard is unintentional. This volume of
24 POSIX.1‐2017 defers to the ISO C standard.
25 The tolower() and tolower_l() functions have as a domain a type int,
27 the value of which is representable as an unsigned char or the value of
28 EOF. If the argument has any other value, the behavior is undefined. If
29 the argument of tolower() or tolower_l() represents an uppercase let‐
30 ter, and there exists a corresponding lowercase letter as defined by
31 character type information in the current locale or in the locale rep‐
32 resented by locale, respectively (category LC_CTYPE), the result shall
33 be the corresponding lowercase letter. All other arguments in the
34 domain are returned unchanged.
35 The behavior is undefined if the locale argument to tolower_l() is the
37 special locale object LC_GLOBAL_LOCALE or is not a valid locale object
38 handle.
39
41 Upon successful completion, the tolower() and tolower_l() functions
42 shall return the lowercase letter corresponding to the argument passed;
43 otherwise, they shall return the argument unchanged.
44
46 No errors are defined.
47 The following sections are informative.
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51 None.
52
54 None.
55
57 None.
58
60 None.
61
63 setlocale(), uselocale()
64 The Base Definitions volume of POSIX.1‐2017, Chapter 7, Locale,
66 <ctype.h>, <locale.h>
67
69 Portions of this text are reprinted and reproduced in electronic form
70 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
71 table Operating System Interface (POSIX), The Open Group Base Specifi‐
72 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
73 Electrical and Electronics Engineers, Inc and The Open Group. In the
74 event of any discrepancy between this version and the original IEEE and
75 The Open Group Standard, the original IEEE and The Open Group Standard
76 is the referee document. The original Standard can be obtained online
77 at http://www.opengroup.org/unix/online.html .
78 Any typographical or formatting errors that appear in this page are
80 most likely to have been introduced during the conversion of the source
81 files to man page format. To report such errors, see https://www.ker‐
82 nel.org/doc/man-pages/reporting_bugs.html .
83IEEE/The Open Group 2017 TOLOWER(3P)