C Program to demonstrate dynamic memory allocation example.

Write a C Program to demonstrate dynamic memory allocation example.
Dynamic memory allocation means you can allocate or relocate (manipulate) the memory at the run time, using malloc, calloc, and realloc functions.
Using malloc, We can allocate block of memory for a variable
Using calloc function, We can allocate multiple blocks of memory for a variable.
We can alter, reassign the allocated memory using the realloc function.
We can releasing the allocated memory using the free function. Read more about C Programming Language .

/***********************************************************
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* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
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*
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***********************************************************/



#include<stdio.h>
#include<stdlib.h>

int main() {
int* grades;
int sum = 0, i, numberOfStudents;
float average;


printf("Enter the number of students: ");
scanf("%d", &numberOfStudents);
getchar();

if((grades = (int*) malloc(numberOfStudents * sizeof(int))) == NULL) {
printf("nError: Not enough memory to allocate grades arrayn");
exit(1);
}

printf("nEnter the grades of %d students (in separate lines):n", numberOfStudents);

for(i = 0; i < numberOfStudents; i++) {
scanf("%d", &grades[i]);
getchar();
}

/* calculate sum */
for(i = 0; i < numberOfStudents; i++)
sum += grades[i];

/* calculate the average */
average = (float) sum / numberOfStudents;

printf("nThe average of the grades of all students is %.2f",
average);

getchar();
return(0);
}

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C program to illustrate the operations of singly linked list.

Data structures using C,
C program to illustrate the operations of singly linked list. Linked list is a data structure in which the objects are arranged in a linear order. Linked List contains group of nodes, in which each node contains two fields, one is data field and another one is the reference field which contains the address of next node. In this program we insert, delete, search, and display the linked list. Read more about C Programming Language .

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#define MAX 30

struct EMP
{
int empno;
char empName[MAX];
char designation[MAX];
struct EMP *next;
};

/*********************************************************************/
/* Function to insert a node at the front of the linked list. */
/* front: front pointer, id: employee ID, name: employee name */
/* desg: Employee designation */
/* Returns the new front pointer. */
/*********************************************************************/

struct EMP* insert(struct EMP *front, int id, char name[], char desg[])
{
struct EMP *newnode;

newnode = (struct EMP*) malloc(sizeof(struct EMP));

if (newnode == NULL)
{
printf("nAllocation failedn");
exit(2);
}
newnode->empno = id;
strcpy(newnode->empName, name);
strcpy(newnode->designation, desg);
newnode->next = front;
front = newnode;
return(front);
} /*End of insert() */

/* Function to display a node in a linked list */
void printNode(struct EMP *p)
{
printf("nEmployee Details...n");
printf("nEmp No : %d", p->empno);
printf("nName : %s", p->empName);
printf("nDesignation : %sn", p->designation);
printf("-------------------------------------n");
} /*End of printNode() */

/* ********************************************************/
/* Function to deleteNode a node based on employee number */
/* front: front pointer, id: Key value */
/* Returns: the modified list. */
/* ********************************************************/

struct EMP* deleteNode(struct EMP *front, int id)
{
struct EMP *ptr;
struct EMP *bptr; /* bptr is pointing to the node behind ptr */


if (front->empno == id)
{
ptr = front;
printf("nNode deleted:");
printNode(front);
front = front->next;
free(ptr);
return(front);
}

for(ptr=front->next, bptr=front; ptr!=NULL; ptr=ptr->next, bptr=bptr->next)
{
if (ptr->empno == id)
{
printf("nNode deleted:");
printNode(ptr);
bptr->next = ptr->next;
free(ptr);
return(front);
}
}
printf("nEmployee Number %d not found ", id);
return(front);
} /*End of deleteNode() */

/*****************************************************************/
/* Function to search the nodes in a linear fashion based emp ID */
/* front: front pointer, key: key ID. */
/*****************************************************************/
void search(struct EMP *front, int key)
{
struct EMP *ptr;

for (ptr = front; ptr != NULL; ptr = ptr -> next)
{
if (ptr->empno == key)
{
printf("nKey found:");
printNode(ptr);
return;
}
}
printf("nEmployee Number %d not found ", key);
} /*End of search() */

/* Function to display the linked list */
void display(struct EMP *front)
{
struct EMP *ptr;

for (ptr = front; ptr != NULL; ptr = ptr->next)
{
printNode(ptr);
}
} /*End of display() */

/* Function to display the menu of operations on a linked list */
void menu()
{
printf("---------------------------------------------n");
printf("Press 1 to INSERT a node into the list n");
printf("Press 2 to DELETE a node from the list n");
printf("Press 3 to DISPLAY the list n");
printf("Press 4 to SEARCH the list n");
printf("Press 5 to EXIT n");
printf("---------------------------------------------n");
} /*End of menu() */

/* Function to select the option */
char option()
{
char choice;

printf("nn>> Enter your choice: ");
switch(choice=getche())
{
case '1':
case '2':
case '3':
case '4':
case '5': return(choice);
default : printf("nInvalid choice.");
}
return choice;
} /*End of option() */

/* The main() program begins */
void main()
{
struct EMP *linkList;
char name[21], desig[51];
char choice;
int eno;

linkList = NULL;

printf("nWelcome to demonstration of singly linked listn");

menu(); /*Function call */

do {
choice = option(); /*to choose oeration to be performed */

switch(choice)
{
case '1': printf("nEnter the Employee Number : ");
scanf("%d", &eno);

printf("Enter the Employee name : ");
fflush(stdin);
gets(name);

printf("Enter the Employee Designation : ");
gets(desig);

linkList = insert(linkList, eno, name, desig);
break;

case '2': printf("nnEnter the employee number to be deleted: ");
scanf("%d", &eno);

linkList = deleteNode(linkList, eno);
break;

case '3': if (linkList == NULL)
{
printf("nList empty.");
break;
}
display(linkList);
break;

case '4': printf("nnEnter the employee number to be searched: ");
scanf("%d", &eno);

search(linkList, eno);
break;

case '5': break;
}
} while (choice != '5');
} /*End fo main()*/
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C program to create a linked list and display the elements in the list.

Data structures using C,
C program to create a linked list and display the elements in the list. Linked list is a data structure in which the objects are arranged in a linear order. Linked List contains group of nodes, in which each node contains two fields, one is data field and another one is the reference field which contains the address of next node. Read more about C Programming Language .

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include <stdio.h>
#include <alloc.h>
#include <stdlib.h>

void main()
{
struct node
{
int num;
struct node *ptr;
};

typedef struct node NODE;

NODE *head, *first, *temp=0;
int count = 0;
int choice = 1;
first = 0;

while(choice)
{
head =(NODE*) malloc(sizeof(NODE));
printf("Enter the data itemn");
scanf("%d", &head-> num);

if(first != 0)
{
temp->ptr = head;
temp = head;
}
else
{
first = temp = head;
}
fflush(stdin);
printf("Do you want to continue(Type 0 or 1)?n");
scanf("%d", &choice);

} /* End of while */

temp->ptr = 0;
temp = first; /* reset temp to the beginning*/
printf("nstatus of the linked list isn");

while(temp!=0)
{
printf("%d=>", temp->num);
count++;
temp = temp -> ptr;
}
printf("NULLn");
printf("No. of nodes in the list = %dn", count);
} /* End of main*/
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