CS101 Lecture 6: Working with Pointers

CS101 Introduction to Programming

• Course name: CS101 Introduction to Programming
• Institution: MedTech, Mediterranean Institute of Technology
• Date: 12/02/2024

Lecture 6: Working with Pointers

• Topic: Working with pointers
• Lecture number: 6

Outlines

• Topic: Pointers
• Topic: Pointers for Inter-Function Communication

Pointers

• Definition: A pointer is a variable that stores/holds the address of another variable of the same data type. It is also known as a locator or indicator that points to an address of a value.
• Data type: A pointer is a derived data type in C.
• Benefits:
  • More efficient in handling arrays and structures.
  • Allows references to functions and helps in passing functions as arguments to other functions.
  • Reduces program execution time.
  • Enables dynamic memory management in C.

Pointers: Declaration Vs Initialization

• Declaration: data_type *pointer_variable_name; (e.g., int *p;)
• Dereference operator: The * operator is used to access the value stored at the memory address. If a pointer p stores the address of a variable, *p gives the value in that location.

Pointers: Initialization of Pointer Variable

• Initialization: Assigning an address of a variable to a pointer variable.
• Example: int *ptr = &a, where a is the variable.

Pointers: Example

• Addresses and values illustration: The pointer variable stores the address, and the dereference operator accesses the value.

Pointers: Summary

• Reference operator (&): Retrieves the address of a variable.
• Dereference operator (*): Accesses the value at the specified address.

Pointers: Dereferencing

• Accessing a variable's value using a pointer: The dereference operator is used to access data at an address pointed to by a pointer.

Pointers: Practice

• Program example for basic pointer operations: A C program is provided to demonstrate basic pointer operations.

Pointers: Solution

• Solution to the practice: The solution to the given C program in the practice question is provided. Output is shown.

Pointers: Examples 1 and 2

• Programs illustrating pointer concepts: Examples in C programs demonstrate various aspects of pointer usage.

Pointers: Exercises and Answers

• Practice problems and solutions: Example problems regarding pointer usage in C. Answers included for the provided exercises.

Pointers for Inter-Function Communication

• Arrays and Pointers: An array's name directly refers to the address of the first element.
• Pointer to an array: A pointer can be used to point to an array.

Pointers to Arrays

• Accessing array elements through pointers: Explain how to traverse and access array elements using pointer arithmetic and the array name.

Relation between Arrays and Pointers

• Array name represents the base address: The array name in C acts as a pointer to the first element.

Pointers for Inter-Function Communication: Example 1 and 2

• Detailed array-pointer examples: Demonstrates array pointer usage in a C program..

Pointers to Void

• Void pointers: Explanation of void pointers; they can hold memory addresses of any type and are generally used for flexibility in function arguments

Pointers to Pointers

• Definition: A pointer variable can hold the address of another pointer.
• Example programs and concepts: Example programs demonstrating pointer to pointers in C using variables.

Memory Allocation Functions

• Dynamic memory allocation: The use of malloc() and calloc() to allocate memory during program execution, emphasizing when each is appropriate.

Difference between static and dynamic memory allocation

• Difference between static and dynamic allocation: Discusses the runtime vs compile-time nature of memory allocation.

Difference between malloc() and calloc()

• malloc() vs calloc() function: Differences in behavior and use of these memory allocation techniques.

Review

• Summary of key programming tasks involving pointers.

Pointers (Extra)

• Additional practice problems (examples): Explanation and solution to pointer-based practice problems relevant to the content.