function
<cctype>
islower
Check if character is lowercase letter
Checks whether c is a lowercase letter.
Notice that what is considered a letter may depend on the locale being used; In the default "C" locale, a lowercase letter is any of: a b c d e f g h i j k l m n o p q r s t u v w x y z.
Other locales may consider a different selection of characters as lowercase characters, but never characters that returns true for iscntrl, isdigit, ispunct or isspace.
For a detailed chart on what the different ctype functions return for each character of the standard ANSII character set, see the reference for the <cctype> header.
In C++, a locale-specific template version of this function (islower) exists in header <locale>.
Parameters
- c
- Character to be checked, casted to an int, or EOF.
Return Value
A value different from zero (i.e., true) if indeed c is a lowercase alphabetic letter. Zero (i.e., false) otherwise.
Example
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| /* islower example */ #include <stdio.h> #include <ctype.h> int main () { int i=0; char str[]="Test String.\n"; char c; while (str[i]) { c=str[i]; if (islower(c)) c=toupper(c); putchar (c); i++; } return 0; }
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Output:
See also
- isupper
- Check if character is uppercase letter (function)
- isalpha
- Check if character is alphabetic (function)
- toupper
- Convert lowercase letter to uppercase (function)
- tolower
- Convert uppercase letter to lowercase (function)