Thread: empty queue

  1. #1
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    empty queue

    I want to write code for the function that create empty queue with no element

    Code:
    #include<stdio.h>
    #include <stdlib.h>
    
    struct Queue {
        struct Node *first;
        struct Node *last;
        
    };
    
    void EmptyQueue(struct Queue *q) {
        q->front = NULL;
        q->last = NULL;
    }
    Is my function a correct ?

  2. #2
    and the hat of int overfl Salem's Avatar
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    Looks good.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  3. #3
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    Quote Originally Posted by Salem View Post
    Looks good.
    next step, I have written code for en queue functions

    Code:
    #include<stdio.h>
    #include <stdlib.h>
    
    
    struct Node {
        int data;
        struct Node *next;
    };
      
    struct Queue {
        struct Node *first;
        struct Node *last;
         
    };
     
    void EmptyQueue(struct Queue *q) {
        q->front = NULL;
        q->last = NULL;
    }
    
    void enqueue(struct Queue *q, int data) {
        
     
        if (q->first == NULL) {
            q->first = (struct Node *) malloc(sizeof(struct Node));
            q->first->data = data;
            q->first->next = NULL;
            q->last = q->first;
        } 
       else {
            q->last->next = (struct Node *) malloc(sizeof(struct Node));
            q->last->next->data = data;
            q->last->next->next = NULL;
            q->last = q->last->next;
        }
    }
    Is my function for enqueue correct ?
    Last edited by vajra11; 12-28-2019 at 07:52 AM.

  4. #4
    and the hat of int overfl Salem's Avatar
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    Did you bother to test it?

    What tests have you done?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  5. #5
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    Quote Originally Posted by Salem View Post
    Did you bother to test it?

    What tests have you done?
    No I haven't, How do I check weather my function are correct or incorrect. I would need to other function two check queue. I wanted to make three function first empty queue, enqueue and dequeue

  6. #6
    and the hat of int overfl Salem's Avatar
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    Well it might be an idea to implement say
    Code:
    void print_queue(struct Queue *q) {
    }
    Then in your main, say
    Code:
    int main ( ) {
        struct Queue queue;
        EmptyQueue(&queue);
        print_queue(&queue);  // What do you expect here?
        enqueue(&queue,1);
        print_queue(&queue);  // What do you expect here?
    }
    Then you start thinking up more test cases.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

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