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Explain malloc function in C programming
Problem
Write a C program to display and add the elements using dynamic memory allocation functions.
Solution
In C, the library function malloc allocates a block of memory in bytes at runtime. It returns a void pointer, which points to the base address of allocated memory and it leaves the memory uninitialized.
Syntax
void *malloc (size in bytes)
For example,
int *ptr;
ptr = (int * ) malloc (1000);
int *ptr;
ptr = (int * ) malloc (n * sizeof (int));
Note − It returns NULL, if the memory is not free.
Example
#include<stdio.h>
#include<stdlib.h>
void main(){
//Declaring variables and pointers,sum//
int numofe,i,sum=0;
int *p;
//Reading number of elements from user//
printf("Enter the number of elements : ");
scanf("%d",&numofe);
//Calling malloc() function//
p=(int *)malloc(numofe*sizeof(int));
/*Printing O/p - We have to use if statement because we have to check if memory has been successfully allocated/reserved or not*/
if (p==NULL){
printf("Memory not available");
exit(0);
}
//Printing elements//
printf("Enter the elements :
");
for(i=0;i<numofe;i++){
scanf("%d",p+i);
sum=sum+*(p+i);
}
printf("
The sum of elements is %d",sum);
free(p);//Erase first 2 memory locations//
printf("
Displaying the cleared out memory location :
");
for(i=0;i<numofe;i++){
printf("%d
",p[i]);//Garbage values will be displayed//
}
}Output
Enter the number of elements : 5 Enter the elements : 23 45 65 12 23 The sum of elements is 168 Displaying the cleared out memory location : 10753152 0 10748240 0 23
Updated on: 06-Mar-2021
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