C Programming Language Overview

C Development and Use

• Developed by Dennis Ritchie at AT&T Laboratories in 1972.
• Originally meant for the UNIX operating system.
• Foundation for several programming languages.
• Applications include operating systems, compilers, assemblers, editors, network drivers, utilities, embedded systems, and general-purpose programs.

C Programming Language Features

• Structured programming language.
• Highly portable - Programs operate independent of platform and operating system choice.
• Blends high-level language features with bit manipulation capabilities.
• Fast compilation and execution speeds.
• Extensible by adding functions to its base set.
• Relatively easy to learn - Consists of only 32 keywords.

C Program Structure

• Comments are optional and ignored by the compiler.
• Preprocessor directive #include is used to access header files (files with extension .h), containing macro definitions and declarations of common C functions.
• The main() function is essential to all C programs.
• Global/local declarations indicate memory requirements.
• Brackets { } group statements and define function bodies - One opening bracket { requires a closing } bracket.
• The return 0; statement ends the program and returns 0 to the operating system indicating normal termination. A non-zero value like 1 indicates abnormal termination.
• C is case-sensitive.

C Language Elements

Character Set

• Alphabets: Uppercase (A-Z) and Lowercase (a-z).
• Digits: 0-9.
• Special characters: ~-'!@#%^&*()_-+=|{}[]:;"',.?/.
• White space characters: Space, newline, horizontal tab, carriage return, form feed.

Keywords (Reserved Words)

• Strictly lowercase.
• Cannot be used as identifiers.

Identifiers

• User-defined names for variables, functions, constants, and other program entities.
• Case-sensitive.
• Must contain letters (uppercase and lowercase), digits, and underscores (_).
• Cannot begin with a digit (0-9).
• Underscore can be used as the first character (e.g., _result).
• Special characters are restricted to underscores.
• Keywords cannot be used as identifiers.
• Length limits are compiler dependent.
• Identifier names should be descriptive, meaningful, and unique.

Function printf()

• Built-in C function for output operations (displaying data on screen, sending to printer or file).
• Defined in the “stdio.h” header file, which must be included when using the function.

Syntax

• printf(“format_string”, variable1, variable2, variable3,...);

Format String Components

• Plain characters: Displayed on the screen as they are.
• Format specifiers: Placeholders replaced by variable values, starting with % followed by a data type code matching the variable data type (e.g., %c for a character variable). There must be one format specifier for each variable, and they are replaced sequentially.
• Escape sequences: Control cursor or insertion point.

Format Specifiers

• Format specifier | Description | Supported data types ------------------- | --------------- | ---------------------------------------- %c | Character | char, unsigned char %d | Signed integer | short, unsigned short, int, long %e or %E | Scientific notation of float values | float, double %f | Floating point | float, double %g or %G | Similar as %e or %E | float, double %i | Signed integer | short, unsigned short, int, long %l or %ld or %li | Signed integer | long %lf | Floating point | double %Lf | Floating point | long double %lu | Unsigned integer | unsigned int, unsigned long %o | Octal representation of integer | short, unsigned short, int, unsigned int, long %p | Address of pointer to void | void * %s | String | char * %u | Unsigned integer | short, unsigned short, int, unsigned int, long %x or %X | Hexadecimal representation of unsigned integer | short, unsigned short, int, unsigned int, long %% | Prints % character |

Escape Sequences

• Escape Sequence | Name | Description ------------------- | ---------------| -------- \a | Alert | Sounds a beep \b | Backspace | Backs up 1 character \f | Form feed | Starts a new screen or page \n | New line | Moves to the beginning of the next line \r | Carriage return | Moves to the beginning of the current line \t | Horizontal tab | Moves to the next tab position \v | Vertical tab | Moves down a fixed amount \ | Back slash | Prints a back slash ' | Single quotation | Prints a single quotation " | Double quotation | Prints a double quotation ? | Question mark | Prints a question mark

This quiz covers key aspects of the C programming language, including its development, features, and structure. Designed by Dennis Ritchie, C laid the foundation for many programming languages and is known for its portability and efficiency. Test your knowledge of this vital language.