C Exercises: Delete first node of Singly Linked List
C Linked List : Exercise-7 with Solution
Write a program in C to delete first node of Singly Linked List.
Pictorial Presentation:
Sample Solution:
C Code:
#include <stdio.h>
#include <stdlib.h>
struct node
{
int num; //Data of the node
struct node *nextptr; //Address of the node
}*stnode;
void createNodeList(int n); //function to create the list
void FirstNodeDeletion(); //function to delete the first node
void displayList(); //function to display the list
int main()
{
int n,num,pos;
printf("\n\n Linked List : Delete first node of Singly Linked List :\n");
printf("------------------------------------------------------------\n");
printf(" Input the number of nodes : ");
scanf("%d", &n);
createNodeList(n);
printf("\n Data entered in the list are : \n");
displayList();
FirstNodeDeletion();
printf("\n Data, after deletion of first node : \n");
displayList();
return 0;
}
void createNodeList(int n)
{
struct node *fnNode, *tmp;
int num, i;
stnode = (struct node *)malloc(sizeof(struct node));
if(stnode == NULL) //check whether the stnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
}
else
{
// reads data for the node through keyboard
printf(" Input data for node 1 : ");
scanf("%d", &num);
stnode-> num = num;
stnode-> nextptr = NULL; //Links the address field to NULL
tmp = stnode;
//Creates n nodes and adds to linked list
for(i=2; i<=n; i++)
{
fnNode = (struct node *)malloc(sizeof(struct node));
if(fnNode == NULL) //check whether the fnnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
break;
}
else
{
printf(" Input data for node %d : ", i);
scanf(" %d", &num);
fnNode->num = num; // links the num field of fnNode with num
fnNode->nextptr = NULL; // links the address field of fnNode with NULL
tmp->nextptr = fnNode; // links previous node i.e. tmp to the fnNode
tmp = tmp->nextptr;
}
}
}
}
void FirstNodeDeletion()
{
struct node *toDelptr;
if(stnode == NULL)
{
printf(" There are no node in the list.");
}
else
{
toDelptr = stnode;
stnode = stnode->nextptr;
printf("\n Data of node 1 which is being deleted is : %d\n", toDelptr->num);
free(toDelptr); // Clears the memory occupied by first node
}
}
void displayList()
{
struct node *tmp;
if(stnode == NULL)
{
printf(" No data found in the list.");
}
else
{
tmp = stnode;
while(tmp != NULL)
{
printf(" Data = %d\n", tmp->num); // prints the data of current node
tmp = tmp->nextptr; // advances the position of current node
}
}
}
Sample Output:
Linked List : Delete first node of Singly Linked List : ------------------------------------------------------------ Input the number of nodes : 3 Input data for node 1 : 2 Input data for node 2 : 3 Input data for node 3 : 4 Data entered in the list are : Data = 2 Data = 3 Data = 4 Data of node 1 which is being deleted is : 2 Data, after deletion of first node : Data = 3 Data = 4
Flowchart:
>
createNodeList():
FirstNodeDeletion() :
displayList() :
C Programming Code Editor:
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Previous: Write a program in C to insert a new node at the middle of Singly Linked List.
Next: Write a program in C to delete a node from the middle of Singly Linked List.
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C Programming: Tips of the Day
Static variable inside of a function in C
The scope of variable is where the variable name can be seen. Here, x is visible only inside function foo().
The lifetime of a variable is the period over which it exists. If x were defined without the keyword static, the lifetime would be from the entry into foo() to the return from foo(); so it would be re-initialized to 5 on every call.
The keyword static acts to extend the lifetime of a variable to the lifetime of the programme; e.g. initialization occurs once and once only and then the variable retains its value - whatever it has come to be - over all future calls to foo().
Ref : https://bit.ly/3fOq7XP
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