Exercise 4-8. Suppose that there will never be more than one character of pushback. Modify getch and ungetch accordingly. The original K&R implementation uses an array buf[BUFSIZE] and an index bufp to support multiple pushed-back characters. If only one character of pushback is ever needed, the array becomes unnecessary. A single static int buf suffices …
Exercise 1-6. Verify that the expression getchar() != EOF is 0 or 1. What This Exercise Is Really About This is not a “write a loop” exercise — it is a verification exercise, and the thing being verified is a fundamental rule of C that surprises many beginners: every relational expression in C evaluates to …
The getchar() function reads a single character from standard input (the keyboard) and returns it. It is one of the simplest input functions in C and a great way to understand how the input buffer works. In this program we use getchar() in a loop to read text entered by the user and count how …
The ctype.h header provides a set of functions for testing and converting individual characters. Each function takes an int (the ASCII value of a character) and returns a non-zero value (true) if the character belongs to a certain class. They are used in parsers, tokenizers, input validation, and any code that processes text character by …