Arrays and Strings

1. Introduction

From JavaScript Arrays to C Arrays

In JavaScript, arrays are dynamic, flexible data structures that can hold mixed types and automatically resize. In C, arrays are fixed-size, contiguous memory blocks that require explicit management but offer superior performance and memory efficiency.

C arrays are fundamental building blocks that form the basis for more complex data structures. Understanding them is crucial for:

• Efficient memory usage
• Performance optimization
• Building custom data structures
• System programming

💡 Key Concept: C arrays are just contiguous blocks of memory. The array name is actually a pointer to the first element, making arrays and pointers closely related in C.

2. Array Basics

2.1 Array Declaration and Initialization

2.2 Arrays and Pointers Relationship

2.3 Array Bounds and Safety

3. Multidimensional Arrays

3.1 2D Arrays

3.2 Higher Dimensional Arrays

4. String Handling

4.1 C Strings vs JavaScript Strings

4.2 String Functions and Safety

4.3 Character Arrays and String Literals

5. Buffer Overflow Prevention

5.1 Understanding Buffer Overflow

5.2 Safe String Functions

6. Practical Examples

6.1 Array Processing Functions

6.2 String Processing Functions

7. Exercises

Exercise 1: Array Operations

Create a C program that:

1. Declares an array of 10 integers
2. Fills it with random numbers
3. Finds the maximum, minimum, and average
4. Sorts the array in ascending order
5. Searches for a specific value

Exercise 2: String Manipulation

Write a C program that:

1. Takes a string input from the user
2. Removes all vowels from the string
3. Converts the result to uppercase
4. Reverses the string
5. Counts the number of consonants

Exercise 3: 2D Array Processing

Create a C program that:

1. Creates a 3x3 matrix
2. Fills it with numbers
3. Calculates the sum of each row and column
4. Finds the maximum value in the matrix
5. Transposes the matrix

8. Summary

Key Concepts Covered

• Array Declaration: Fixed-size, contiguous memory blocks
• Array-Pointer Relationship: Arrays decay to pointers
• Multidimensional Arrays: 2D and 3D array handling
• String Handling: Character arrays with null termination
• Buffer Safety: Preventing buffer overflow attacks
• String Functions: Safe string manipulation

JavaScript vs C Differences

• Dynamic vs Fixed Size: JavaScript arrays grow/shrink, C arrays are fixed
• Bounds Checking: JavaScript has automatic bounds checking, C requires manual checking
• String Handling: JavaScript strings are objects, C strings are character arrays
• Memory Management: JavaScript is automatic, C requires explicit management

Best Practices

1. Always check array bounds before accessing elements
2. Use safe string functions to prevent buffer overflow
3. Initialize arrays properly to avoid undefined behavior
4. Validate input before processing strings
5. Use sizeof() to calculate array sizes safely
6. Handle null termination properly in strings

Next Steps

In the next module, we'll explore Functions and Stack Management, where you'll learn how functions work in C, parameter passing mechanisms, and how the call stack operates - concepts that are hidden from JavaScript developers but crucial for understanding C's memory model.