tolower
From cppreference.com
| Defined in header <ctype.h>
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int tolower( int ch );
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Converts the given character to lowercase according to the character conversion rules defined by the currently installed C locale.
In the default "C" locale, the following uppercase letters ABCDEFGHIJKLMNOPQRSTUVWXYZ are replaced with respective lowercase letters abcdefghijklmnopqrstuvwxyz.
Parameters
| ch | - | character to be converted. If the value of ch is not representable as unsigned char and does not equal EOF, the behavior is undefined.
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Return value
Lowercase version of ch or unmodified ch if no lowercase version is listed in the current C locale.
Example
Run this code
#include <ctype.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
int main(void)
{
// In the default locale
for (unsigned char u = 0; u < UCHAR_MAX; u++)
{
unsigned char l = tolower(u);
if (l != u)
printf("%c%c ", u, l);
}
printf("\n\n");
unsigned char c = '\xb4'; // the character Ž in ISO-8859-15
// but ´ (acute accent) in ISO-8859-1
setlocale(LC_ALL, "en_US.iso88591");
printf("in iso8859-1, tolower('0x%x') gives 0x%x\n", c, tolower(c));
setlocale(LC_ALL, "en_US.iso885915");
printf("in iso8859-15, tolower('0x%x') gives 0x%x\n", c, tolower(c));
}
Possible output:
Aa Bb Cc Dd Ee Ff Gg Hh Ii Jj Kk Ll Mm Nn Oo Pp Qq Rr Ss Tt Uu Vv Ww Xx Yy Zz
in iso8859-1, tolower('0xb4') gives 0xb4
in iso8859-15, tolower('0xb4') gives 0xb8
References
- C23 standard (ISO/IEC 9899:2024):
- 7.4.2.1 The tolower function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.4.2.1 The tolower function (p: 147)
- C11 standard (ISO/IEC 9899:2011):
- 7.4.2.1 The tolower function (p: 203)
- C99 standard (ISO/IEC 9899:1999):
- 7.4.2.1 The tolower function (p: 184)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.3.2.1 The tolower function
See also
| converts a character to uppercase (function) | |
(C95) |
converts a wide character to lowercase (function) |
C++ documentation for tolower
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