C Programming: Memory Basics and Pointer Arithmetic

10 Questions

What happens when you assign the address of an array to a pointer?

The pointer points to the first element of the array

What is the purpose of the dereference operator?

To access the value at the pointer's address

What happens when you reassign a pointer to a different variable?

The pointer is reassigned to the new variable's address

What is an example of pointer arithmetic?

Incrementing a pointer to point to the next element in an array

What is the result of the statement `*outcome = 63`?

The value at the address pointed to by outcome is changed to 63

What is the purpose of initializing variables in a program?

To give the variable a desired value

What does the `sizeof` operator determine?

The memory size of variables or data structures

What is the purpose of the `&` operator in C?

To fetch the memory address of a variable

What is the syntax to declare a pointer variable in C?

int *p;

What is the value of uninitialized variables in C?

Garbage value

Study Notes

Memory Basics

Memory stores information for the computer.
Variables are assigned memory space based on their type when declared.
Uninitialized variables hold whatever value is at their memory location.
It's essential to initialize variables to give them a desired value.

Variable Declaration and Initialization

Declaring variables without initialization can lead to unpredictable values.
Example: a program demonstrating variables without initialization can print unexpected values.

Sizeof Operator

The sizeof operator determines the memory size of variables or data structures.
Example: sizeof(array) returns 40 for an array of 10 integers.

Memory Address of Variables

The & operator fetches the memory address of a variable.
Example: &c returns the memory location of a char variable c.

Pointers

Pointer Basics

A pointer is a variable that holds a memory address.
Declared with a type and an asterisk (*).
Example: float *p_euros; declares a pointer to a float.

Pointer Initialization

Assign the address of a variable to a pointer.
Example: p_euros = &euros; assigns the address of euros to p_euros.

Pointers and Arrays

Pointers can hold the address of the first element of an array.
Example: a = array; assigns the address of the first element of array to a.

Dereferencing Pointers

Use the dereference operator (*) to access the value at the pointer's address.
Example: *point1 accesses the value of var1 through the pointer point1.

Manipulating Memory with Pointers

Pointers can be reassigned to different variables.
Example: outcome is reassigned to point to group1 and then group2.

Pointer Arithmetic

Basic Pointer Arithmetic

Incrementing a pointer makes it point to the next memory location.
Example: pa is incremented to point to the next short int in the array.

Pointer Arithmetic Operations

Pointers can be incremented, decremented, or modified using arithmetic operators.
Example: pa = pa + 2 increments the pointer to point to the third element in the array.