Unit 3: Unformatted and Formatted I/O

1. Introduction to I/O Functions

Input/Output (I/O) functions are essential for interaction between the user and the computer. In C, these functions are categorized based on whether they allow the user to control the format of the data being transferred.

• Input: Sending data into a program from a keyboard or file.
• Output: Displaying or storing the results of a program.

2. Formatted I/O: printf() and scanf()

Formatted functions allow the programmer to specify exactly how the data should be read or displayed using format specifiers.

printf() Function

Used to send formatted output to the standard output device (usually the screen).

printf("format string", argument_list);
// Example: printf("Age is %d", age);
    

scanf() Function

Used to read formatted input from the standard input device (usually the keyboard).

scanf("format string", &argument_list);
// Example: scanf("%d", &age);
    

Common Format Specifiers

3. Unformatted I/O: Character and String Functions

Unformatted I/O functions work with individual characters or strings of characters without using format specifiers.

Character I/O

• getchar(): Reads a single character from the keyboard.
• putchar(): Displays a single character on the screen.

String I/O

• gets(): Reads a string (including spaces) from the keyboard until a newline is reached.
• puts(): Displays a string on the screen and automatically moves the cursor to a new line.

4. Expressions in C

An expression is a combination of operators, constants, and variables arranged according to the rules of the language.

Definition: An expression evaluates to a single value. For example, a + b is an arithmetic expression.

• Operands: The data elements (variables or constants) on which operations are performed.
• Operators: Symbols that trigger specific mathematical or logical actions.

5. Exam Focus Enhancements