C Exercises: Allocate a block of memory for an array

Last update on July 29 2025 12:55:11 (UTC/GMT +8 hours)

11. Dynamic Memory Allocation for an Array

Write a C program to allocate a block of memory for an array.

Sample Solution:

C Code:

#include<stdio.h>      // Include the standard input/output header file.
#include<stdlib.h>     // Include the standard library header file.

int main ()          // Start of the main function.
{
int i, n, num;    // Declare integer variables 'i', 'n', and 'num'.
int * my_array;   // Declare a pointer to int 'my_array'.

printf("\nInput the number of elements to be stored in the array :");   // Prompt the user to input the number of elements.
scanf("%d",&n);   // Read the user's input and store it in 'n'.

printf("Input %d elements in the array :\n",n);   // Prompt the user to input the elements of the array.

my_array = (int*) calloc( n,sizeof(int) );   // Allocate memory for 'n' integers and assign the pointer to 'my_array'.
if (my_array==NULL)   // Check if memory allocation was successful.
    {
printf (" Requested memory allocation is wrong.");   // Print an error message if memory allocation failed.
exit (1);   // Exit the program with an error code.
    }

for ( i=0; i<n; i++ )   // Start of a for loop to iterate over the elements of the array.
    {
printf (" element %d : ",i+1);   // Prompt the user for the value of the current element.
scanf ("%d",&my_array[i]);     // Read the user's input and store it in the current element of 'my_array'.
    }

printf (" Values entered in the array are : \n");   // Print a message indicating the values in the array.
for ( i=0; i<n; i++ )   // Start of a for loop to iterate over the elements of the array.
printf (" %d ",my_array[i]);   // Print the current element of the array.

printf ("\n\n");   // Print two newline characters for formatting.

free (my_array);   // Free the allocated memory for 'my_array'.

return 0;   // Return 0 to indicate successful execution of the program.
}   // End of the main function.

Sample Output:

Input the number of elements to be stored in the array :5                                                     
Input 5 elements in the array :                                                                               
 element 1 : 5                                                                                                
 element 2 : 10                                                                                               
 element 3 : 15                                                                                               
 element 4 : 20                                                                                               
 element 5 : 25                                                                                               
 Values entered in the array are :                                                                            
 5  10  15  20  25

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to dynamically allocate memory for an array of integers and initialize it with user inputs.
Write a C program to allocate memory using calloc() for an array and then expand it with realloc() as needed.
Write a C program to allocate a block of memory for an array, fill it with random numbers, and then free the memory.
Write a C program to allocate memory for an array of doubles, populate it, and display the results, ensuring no memory leaks.

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