Untitled Quiz

C Language Overview

• C is a powerful and versatile programming language.
• C is a general-purpose language used for systems programming, application development, and embedded systems.

Facts about C

• C is a structured programming language.
• C was developed by Dennis Ritchie at Bell Labs in the 1970s.
• C is a middle-level language.
• C is a compiled language.
• C is a procedural programming language.

Why to use C?

• C is a powerful language that can be used to create a wide variety of software.
• C is very portable and is used on a wide range of computer platforms.
• C is very efficient and is often used for systems programming.

C Programs

• C programs consist of a series of instructions that are executed by the computer.
• The instructions are written in a syntax that the C compiler can understand.
• C programs are saved in files with the .c extension.

C Environment Setup

• To write and run C programs, you need a text editor, a C compiler, and a linker.

Text Editor

• A text editor is used to create and edit C programs.
• Examples of text editors include Notepad++, Sublime Text, and Vim.

The C Compiler

• A C compiler translates your C code into machine instructions.
• The machine instructions are then executed by the computer.
• Examples of C compilers include GCC, Clang, and MSVC.

C Program Structure

• A C program typically consists of functions that are executed in a specific order.
• The most important function is called main(), which is the entry point for the program.
• Generally, code in C is organized into functions and blocks.

C Hello World Example

• A Hello World program simply displays "Hello World" on the computer screen.
• This is the most common first program written in any programming language.

Compile & Execute C Program

• To compile a C program, you need to use a C compiler, such as GCC or Clang.
• To execute a C program, you need to run the compiled executable file.

C Basic Syntax

• C syntax is a set of rules that define the structure of a C program.
• The syntax of the C language is based on the syntax of the B programming language.

Tokens in C

• Tokens are the smallest individual units of the C language.
• Tokens are classified into keywords, identifiers, constants, strings, and special symbols.

Semicolons ;

• Semicolons are used to separate statements in C programs.
• A complete C statement must end with a semicolon.

Comments

• Comments are explanations written inside the code to make the program more readable.
• The compiler ignores comments.
• The /* */ symbol is used to denote a multi-line comment.
• The // symbol is used for single-line comments.

Identifiers

• Identifiers are used to name variables, functions, constants, data types, and labels.
• Identifiers can be any combination of letters, digits, and underscores.
• You cannot use keywords as identifiers.

Keywords

• Keywords are reserved words in C that have specific meanings and cannot be used as identifiers.
• There are 32 keywords in the C programming language.

Whitespace in C

• Whitespace characters are spaces, tabs, and newlines that are used to separate words and tokens.
• Whitespace is ignored by the C compiler but enhances readability.

C Data Types

• Data types are used to define the type of data that a variable can hold.
• They specify how the data is stored in memory.
• Data types determine the operations that can be performed on the data.

Integer Types

• Integer types are used to store whole numbers.
• Examples of integer types include int, short, long, and char.

Floating-Point Types

• Floating-point types are used to store numbers with decimal points.
• Examples of floating-point types include float, double, and long double.

The void Type

• The void type is used to indicate that a function does not return any value.
• void can also be used to declare a pointer that can point to any data type.

C Variables

• Variables are used to store data in memory.
• Every variable in C has a data type, and the data type determines the size and type of data that can be stored in the variable.

Variable Declaration in C

• Variable declaration defines the type and name of a variable.
• Defining a variable creates an empty box in computer memory with the specified name and type to store the data.

Variable Initialization in C

• Variable initialization assigns a value to a variable at the time of declaration.
• Assigning a value fills the empty box - the variable - created in memory.

Lvalues and Rvalues in C

• An lvalue represents a memory location.
• You can access an lvalue with an address operator (&).
• An rvalue represents the value stored in a memory location.
• Only rvalues are allowed in C and cannot be modified.

C Constants and Literals

• A constant is a fixed value that cannot be changed during the execution of the program.
• Literals are constant values that directly appear in the code.

Integer literals

• Integer literals are whole numbers that can be expressed in decimal, octal, or hexadecimal formats.

Floating-point literals

• Floating-point literals are numbers with decimal points.
• They can be expressed in exponential notation using the scientific notation.

Character constants

• Character constants are single characters enclosed in single quotes.
• For example, 'A' is a character constant denoting the letter A.

String literals

• String literals are sequences of characters enclosed in double quotes.
• For example, "Hello World" is a string literal.

Defining Constants

The #define Preprocessor

• You can use the #define directive to define a constant.
• The #define directive is not a statement in C so it does not require a semicolon.
• This directive is processed by the preprocessor during the compilation stage.

The const Keyword

• You can define constants using the const keyword.
• Defining a constant with const keyword is a statement in C.
• You need to specify the data type for the constant.

C Storage Classes

• Storage classes specify the scope, lifetime, and linkage of a variable.
• The scope defines the region within the program where the variable can be accessed.
• The lifetime defines the period for which the variable exists in memory.
• Linkage determines whether the variable is accessible from other files or modules.

The auto Storage Class

• Variables declared with auto storage class have automatic storage duration.
• These variables are allocated space in the stack when the block of code is entered.
• The automatic storage is available only within a block.
• A local variable not initialized explicitly is auto by default.

The register Storage Class

• Variables declared with the register storage class are stored in the register of the CPU, if available.
• This is often done to improve performance because accessing registers is faster than RAM.
• The register variables are only available to the function in which they are declared.
• The compiler may not honor the register storage class, especially if there are no registers available.
• The register variable is not always stored in the register, but is stored in the RAM.