The ctype functions test and convert characters. The functions whose names begin with "is" return a non-zero, true, or zero, false, value depending on whether the test is passed. Ctype functions are called such after the ctype.h header file. The function test for alphabetic, numeric, space, and other specific types of characters.
- [Narrator] The C library comes with a host … of functions to test characters, … determining their type or category. … These are often called the C-type functions … after the header file name ctype.h. … Those C-type functions that test … characters are often referred to … as the IS functions because their … names begin with the letters I and S. … These functions return zero or false … when the test fails and they return … a non-zero or true value otherwise. … Here are some common character-testing functions. … For example isalpha tests to determine … whether a character is alphabetic, … A to Z, upper- or lower- case. … Isdigit returns true for number characters … zero through nine. … Isupper and islower returns true … for upper- and lower-case letters respectively. … And here are some more C-type functions. … Your compiler's C-library may support … some or all of these or even more. … In this file I've written a test string … declared at line six. … It contains a smattering of characters. …
- Working with arrays
- Building a structure
- Creating an array of structures
- Testing characters
- Working with strings in C
- Using pointers to manipulate data
- Manipulating files
- Using command-line arguments
- Working with time functions
Skill Level Intermediate
1. Arrays and Structures
2. Characters and Strings
4. Files and the Operating System
5. The Interesting and Extraordinary
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