char/int. Some parameters have the const attribute, but it's
not indicated below.
Because these are the original C functions, bool isn't used.
Instead, zero is false and non-zero is true.
| Type | Method | Description |
|---|---|---|
#include <cctype> (or older <ctype.h>) | ||
| int | isalnum(c) |
true if c is a letter or digit. |
| int | isalpha(c) |
true if c is a letter. |
| int | isblank(c) |
true if c is a blank or tab. |
| int | isdigit(c) |
true if c is a digit. |
| int | islower(c) |
true if c is a lowercase letter. |
| int | isupper(c) |
true if c is an uppercase letter. |
| int | isspace(c) |
true if c is whitespace character (space, tab, vertical tab, formfeed, carriage return, or newline). |
| int | tolower(c) |
returns lowercase version of c if there is one, otherwise it returns the character unchanged. |
| int | toupper(c) |
returns uppercase version of c if there is one, otherwise it returns the character unchanged. |