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);
}