Dynamic Memory allocation using malloc and calloc

Introduction to dynamic memory allocation and use of DMA functions malloc(), calloc(), free(), etc. [Construct a structure for students having roll number, name, and marks; ask the user for the number of students, allocate memory run time, get all data and print given data in table format.]

1. DMA using malloc()

#include<stdio.h>

#include<stdlib.h>

struct stud{

    int num, marks;

    char name[30];

};

void main(){

    int i, n;

    struct stud *p;

    printf("How many number of students:");

    scanf("%d",&n);

    p = (struct stud*) malloc (n*sizeof(struct stud));

    

    if(p==NULL){

        printf("\nMemory not available..");

    }

    printf("Enter Student Details:");

    for(i=0;i<n;i++)

    {

        printf("\nEnter Number:");

        scanf("%d",&p[i].num);

        printf("Enter Name:");

        scanf("%s",&p[i].name);

        printf("Enter Marks:");

        scanf("%d",&p[i].marks);

    }

    printf("\nStudent Details\n Number\t Name\t Marks");

    for(i=0;i<n;i++)

    {

        printf("\n%d\t%s\t%d",p[i].num,p[i].name,p[i].marks);

    }

     free(p);

}

2. DMA using calloc()

#include<stdio.h>

#include<stdlib.h>

struct stud{

    int num,marks;

    char name[30];

};

void main(){

    int i,n;

    struct stud *p;

    printf("How many number of students:");

    scanf("%d",&n);

    p = (struct stud*) malloc (n*sizeof(struct stud));

    //p = (struct stud*) calloc (n,sizeof(struct stud));

    if(p==NULL){

        printf("\nMemory not available..");

    }

    printf("Enter Student Details:");

    for(i=0;i<n;i++)

    {

        printf("\nEnter Number:");

        scanf("%d",&p[i].num);

        printf("Enter Name:");

        scanf("%s",&p[i].name);

        printf("Enter Marks:");

        scanf("%d",&p[i].marks);

    }

    printf("\nStudent Details\n Number\t Name\t Marks");

    for(i=0;i<n;i++)

    {

        printf("\n%d\t%s\t%d",p[i].num,p[i].name,p[i].marks);

    }

     free(p);

}