Programming in C (312303): Detailed Notes & Question Bank

Unit I: Basics of ‘C’ Programming

1.1 Fundamentals of Algorithms

An algorithm is a step-by-step procedure to solve a specific problem. It acts as a blueprint for your code. Before writing any program, it is crucial to define the logic clearly.

• Pseudocode: Writing the logic in simple English-like statements (e.g., "Set X = 5").
• Flowcharts: Graphical representation using standard symbols (Ovals for Start/Stop, Parallelograms for Input/Output, Rectangles for Process, Diamonds for Decision).

1.2 Structure of a C Program

A C program has a specific structure that the compiler expects:

1.3 Variables, Constants, and Data Types

Variables are named storage locations in memory (e.g., int age = 20;).
Constants are fixed values that do not change during execution (e.g., const float PI = 3.14;).

Basic Data Types:

• int: Integers (whole numbers). Size: 2 or 4 bytes.
• float: Decimal numbers. Size: 4 bytes.
• char: Single characters. Size: 1 byte.
• double: Large decimal numbers. Size: 8 bytes.

1.4 Input and Output Functions

The stdio.h library provides functions for communication with the user:

• printf("formatting string", variables);: Used to display output to the screen.
• scanf("format specifier", &variable);: Used to take input from the user. Note the usage of & (address-of operator).

Unit II: Control Structures

2.1 Conditional Branching

Decision-making structures allow the program to execute code blocks based on conditions:

• if (condition) { ... }: Executes code if the condition is true.
• if-else: Executes the 'if' block if true, otherwise executes the 'else' block.
• else-if ladder: Checks multiple conditions in sequence.
• switch: Selects one of many code blocks to be executed (often used for menu-driven programs).

2.2 Loops (Iterative Statements)

Loops are used to repeat a block of code multiple times:

• while loop: Entry-controlled. Checks condition first, then executes.
• do-while loop: Exit-controlled. Executes once, then checks condition. Essential for menu-driven programs.
• for loop: Best when the number of iterations is known (Initialization; Condition; Update).

2.3 Jump Statements

Used to transfer control unconditionally:

• break;: Exits the loop or switch immediately.
• continue;: Skips the current iteration and moves to the next one.
• goto label;: Jumps to a labeled part of the code (generally discouraged).

Unit III: Arrays & Structures

3.1 Arrays

An Array is a collection of elements of the same data type stored in contiguous memory locations.

One-Dimensional Array: List of items (e.g., Marks of 5 students).
int marks[5];

Two-Dimensional Array: Grid or Matrix format (Rows x Columns).
int matrix[3][3];

3.2 Strings

In C, a String is simply a character array terminated by a null character '\0'.
Common operations include finding length (strlen), copying (strcpy), and concatenating (strcat).

3.3 Structures

A Structure allows you to combine data of different types under a single name. Consider a student record:

We can create an Array of Structures to store records for multiple students efficiently.

Unit IV: Functions

4.1 Need for Functions

Functions allow modularity. They break large programs into smaller, manageable, and reusable pieces ("Divide and Conquer").

4.2 Types of Functions

• Library Functions: Pre-defined functions (e.g., printf(), sqrt(), strlen()).
• User-Defined Functions: Functions created by the programmer to perform specific tasks.

4.3 Parameter Passing

• Call by Value: Value of arguments is copied. Changes in the function do not affect the original variable.
• Call by Reference: Address of arguments is passed. Changes do affect the original variable.

4.4 Recursion

Recursion occurs when a function calls itself. It needs a base case to stop infinite looping. Example: Factorial calculation (5! = 5 * 4!).

Unit V: Pointers

5.1 Introduction to Pointers

A Pointer is a variable that stores the memory address of another variable. It is a powerful feature for direct memory manipulation.

• & (Address-of Operator): Returns the address of a variable.
• * (Dereference Operator): Accesses the value stored at the address.

5.2 Pointer Arithmetic

We can perform addition and subtraction on pointers. Incrementing an integer pointer (ptr++) moves it forward by 4 bytes (depending on system architecture), pointing to the next integer location.

Exam Question Bank (Important)