Why dynamic memory is needed - See It in Action

Why Dynamic Memory is Needed

📖 Scenario: Imagine you are building a program that stores names of students in a class. Sometimes the class size changes, and you don't know the number of students before running the program.

🎯 Goal: You will create a simple C program that uses dynamic memory to store student names. This will show why dynamic memory is needed when the amount of data is not fixed.

📋 What You'll Learn

Create a pointer to hold student names dynamically

Use malloc to allocate memory for 3 student names

Add a variable to store the number of students

Use a loop to assign names to the allocated memory

Print the stored student names

💡 Why This Matters

🌍 Real World

Programs often need to handle data that changes size, like user input lists or files. Dynamic memory helps manage this efficiently.

💼 Career

Understanding dynamic memory is essential for C programmers working on system software, embedded devices, or performance-critical applications.

1

Create a pointer for student names

Declare a pointer called students of type char ** to hold multiple student names.

C

// Declare a pointer for student names
// Your code here

Need a hint?

Use char **students; to declare a pointer to an array of strings.

2

Set number of students and allocate memory

Create an integer variable called num_students and set it to 3. Then use malloc to allocate memory for students to hold 3 pointers to char.

C

char **students;
// Set number of students
// Your code here

Need a hint?

Use malloc to allocate memory for 3 pointers to strings.

3

Allocate memory for each student name and assign names

Use a for loop with variable i from 0 to num_students - 1. Inside the loop, allocate memory for each student name to hold 20 characters using malloc. Then assign these exact names: "Anna", "Ben", "Cara" to students[0], students[1], and students[2] respectively using strcpy.

C

char **students;
int num_students = 3;
students = (char **)malloc(num_students * sizeof(char *));
// Allocate memory for each student name and assign names
// Your code here

Need a hint?

Use a loop to allocate memory for each name, then use strcpy to copy the names.

4

Print the student names

Use a for loop with variable i from 0 to num_students - 1. Inside the loop, print each student name stored in students[i] using printf.

C

char **students;
int num_students = 3;
students = (char **)malloc(num_students * sizeof(char *));
for (int i = 0; i < num_students; i++) {
    students[i] = (char *)malloc(20 * sizeof(char));
}
strcpy(students[0], "Anna");
strcpy(students[1], "Ben");
strcpy(students[2], "Cara");
// Print each student name
// Your code here

Need a hint?

Use a loop and printf to show each name.