---

---

---

TOUPPER

Section: Linux Programmer's Manual (3)
Updated: 1993-04-04
Index Return to Main Contents

---

 

NAME

toupper, tolower - convert letter to upper or lower case  

SYNOPSIS

#include <ctype.h>

int toupper(int c);


int tolower(int c);

 

DESCRIPTION

toupper() converts the letter c to upper case, if possible.

tolower() converts the letter c to lower case, if possible.

If c is not an unsigned char value, or EOF, the behavior of these functions is undefined.  

RETURN VALUE

The value returned is that of the converted letter, or c if the conversion was not possible.  

CONFORMING TO

C89, C99, 4.3BSD.  

BUGS

The details of what constitutes an uppercase or lowercase letter depend on the current locale. For example, the default C locale does not know about umlauts, so no conversion is done for them.

In some non-English locales, there are lowercase letters with no corresponding uppercase equivalent; the German sharp s is one example.  

SEE ALSO

isalpha(3), setlocale(3), towlower(3), towupper(3), locale(7)  

COLOPHON

This page is part of release 3.35 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man-pages/.

---

 

Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

CONFORMING TO

BUGS

SEE ALSO

COLOPHON

---

---

---