CSE115L Programming Language I Lab

Dynamic Memory Allocation

In this lab, we will learn about dynamic memory allocation in C. An array is a collection of a fixed number of values. Once the size of an array is declared, you cannot change it. Sometimes the size of the array you declared may be insufficient. To solve this issue, you can allocate memory manually during run-time. This is known as dynamic memory allocation in C programming. C provides 4 library functions for this purpose. These are defined in the header file. The functions are: 1. malloc(): The malloc or memory allocation function is used to dynamically allocate a single large block of memory with the specified size. It returns a pointer of type void which can be cast into a pointer of any form. The general syntax is as follows. ptr = (cast-type*) malloc(byte-size); If the space is insufficient, allocation fails and returns a NULL pointer. 2. calloc(): The calloc or contiguous allocation function is used to dynamically allocate the specified number of blocks of memory of the specified type. It initializes each block with a default value 0. The general syntax is as follows. ptr = (cast-type*) calloc(n, element-size); If the space is insufficient, allocation fails and returns a NULL pointer. 3. free(): The free function is used to dynamically de-allocate the memory. The memory allocated using functions malloc() and calloc() are not de-allocated on their own. Hence the free() function is used, whenever the dynamic memory allocation takes place. It helps to reduce wastage of memory by freeing it. The general syntax is as follows. free(ptr); 4. realloc(): The realloc or re-allocation function is used to dynamically change the memory allocation of a previously allocated memory. In other words, if the memory previously allocated with the help of malloc() or calloc() is insufficient, realloc() can be used to dynamically re-allocate memory. The general syntax is as follows. ptr = realloc(ptr, newSize); If the space is insufficient, allocation fails and returns a NULL pointer. On the next page, you will find an example program showing the usage of all 4 of these functions. Perform the following tasks.

Task 1. Implement the following function which accepts an integer parameter n and returns an array containing all the elements from the first to the nth Fibonacci numbers. int* getFibonacciSequence(int n);

Task 2: In the main function, read an integer from the user and pass it to the getFibonacciSequence function. Then print the Fibonacci numbers from the returned array.

For Example

Usage of malloc(), calloc(), free() and realloc().

#include #include int main() { // This pointer will hold the base address of the block created int *ptr; int i, size, newSize; // Get the number of elements for the array printf("Enter number of elements: "); scanf("%d", &size); // Dynamically allocate memory using calloc() or malloc() ptr = (int*)malloc(size * sizeof(int)); // Or you can use calloc() //ptr = (int*)calloc(size, sizeof(int)); // Check if the memory has been successfully allocated or not if (ptr == NULL) { printf("Memory cannot be allocated. "); } else { // Memory has been successfully allocated printf("Memory successfully allocated using malloc. "); // Get the elements of the array for (i = 0; i < size; ++i) ptr[i] = i + 1; // Print the elements of the array printf("The elements of the array are: "); for (i = 0; i < size; ++i) printf("%d, ", ptr[i]); // Get the new size for the array printf(" Enter the new size of the array: "); scanf("%d", &newSize); // Dynamically re-allocate memory using realloc() ptr = realloc(ptr, newSize * sizeof(int)); if(ptr != NULL){

// Memory has been successfully allocated printf("Memory successfully re-allocated using realloc. "); // Get the new elements of the array for (i = size; i < newSize; ++i) ptr[i] = i + 1; // Print the elements of the array printf("The elements of the array are: "); for (i = 0; i < newSize; ++i) printf("%d, ", ptr[i]); } else printf("Memory cannot be reallocated. ");

free(ptr); } return 0; }

Please answer task 1 and 2 by using C language (Dynamic Memory Allocation)