C Language Chapter Overview

C Language Overview

• C is a widely-used programming language that provides low-level access to memory and is suitable for system programming.
• Programs in C are structured using functions, variables, and control structures, allowing for detailed manipulation of data.

Variables

• A variable is a named memory location used to store data.
• Rules for naming variables:
  • Case-sensitive (e.g., Var and var are different).
  • Must start with an alphabet or underscore (_).
  • Cannot contain spaces or special characters, except underscores.
• Example of variable declaration:

  int number = 25;
  

Data Types

• Defines the type of data a variable can hold, affecting memory usage and operations.
• Common data types and their sizes:
  • char: 1 byte
  • int: 2 bytes
  • float: 4 bytes
  • double: 8 bytes
  • long: 4 bytes
• C does not have built-in boolean or string data types.

Constants

• Constants are values that do not change during program execution.
  • Types include:
    • Integer Constants: e.g., 1, -2
    • Real Constants: e.g., 2.0, -24.8
    • Character Constants: e.g., 'a', '#'

Keywords

• Reserved words with special meaning in C, totaling 32, including:
  • auto, break, char, if, else, for, void, while, return
• Keywords cannot be used as identifiers for variables or functions.

Program Structure

• Basic structure of a C program includes preprocessor directives, a main function, and return statement.

  #include <stdio.h>
  int main() {
      printf("Hello World");
      return 0;
  }
  

Comments

• Used to annotate code, improving readability.
  • Single-line: // comment
  • Multi-line: /* comment */

Input and Output

• Outputs data with printf function, supports various format specifiers:
  • Integers: %d
  • Floats: %f
  • Characters: %c
• Inputs data with scanf function using the corresponding format specifiers.

Compilation Process

• The C source file is converted into an executable by a compiler.
  • e.g., Hello.c compiles to a.exe (Windows) or a.out (Linux/macOS).

Instructions and Operators

• C instructions are statements executed by the computer, including type declarations and arithmetic operations.
• Types of operators include:
  • Arithmetic: +, -, *, /, %
  • Relational: ==, !=, >, <, >=, <=
  • Logical: &&, ||, !

Arithmetic Operations

• Utilizes operators for performing calculations:
  • Example: a + b adds values of a and b.
• Modulo operator (%) returns the remainder of a division.
  • Example: 5 % 3 results in 2.

Variable Assignment and Expressions

• Variables can be assigned values using =.
• Expressions can combine variables and constants to compute values.

Control Flow

• C provides control instructions for program execution flow:
  • Sequence Control
  • Decision Control (e.g., if, else)
  • Loop Control (e.g., for, while)

Type Conversion

• Implicit Conversion is performed by the compiler when mixing different data types.
• Explicit conversion requires manual intervention by the programmer.
• Operations on different types follow specific rules, impacting the output type.

Operator Precedence and Associativity

• Operator precedence determines the order in which operations are performed:
  • Highest: *, /, %
  • Lower: +, -
• Associativity for operators is left to right, affecting evaluation order in expressions.

Program Example

• Summation program to demonstrate C syntax:

  #include <stdio.h>
  int main() {
      int a, b;
      printf("Enter a: ");
      scanf("%d", &a);
      printf("Enter b: ");
      scanf("%d", &b);
      int sum = a + b;
      printf("Sum is: %d", sum);
      return 0;
  }
  

This quiz covers the fundamental topics in C programming, including variables, data types, and control statements. It goes through essential concepts such as functions, pointers, arrays, and file handling, designed for learners at all levels. Test your knowledge of C programming concepts and enhance your understanding of this powerful language.