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  1. #include<stdio.h>
  2. #include<stdlib.h>
  3.  
  4. struct data {
  5.   struct data *next;
  6.   char key;
  7. };
  8.  
  9. struct queue {
  10.   struct data *top,*rear;
  11. };
  12.  
  13. void enqueue(struct queue *q, char key);
  14. char dequeue(struct queue *q);
  15. void print_queue_list(struct queue q);
  16.  
  17. int main() {
  18.   struct queue q;
  19.   q.top = NULL;
  20.   q.rear = NULL;
  21.  
  22.   enqueue(&q, 'a');
  23.  
  24.   print_queue_list(q);
  25.   printf("\n");
  26.  
  27.   enqueue(&q, 'b');
  28.  
  29.   print_queue_list(q);
  30.   printf("\n");
  31.  
  32.   dequeue(&q);
  33.  
  34.   print_queue_list(q);
  35.   printf("\n");
  36.  
  37.   dequeue(&q);
  38. }
  39.  
  40. void enqueue(struct queue *q, char key) {
  41.   struct data *d;
  42.   d = (struct data *) malloc(sizeof(struct data));
  43.   d->key = key;
  44.   d->next = NULL;
  45.   if (q->top == NULL) {
  46.     q->top = d;
  47.     q->rear = d;
  48.   } else {
  49.     q->rear->next = d;
  50.     q->rear = d;
  51.   }
  52. }
  53.  
  54. char dequeue(struct queue *q) {
  55.   char key;
  56.   struct data *d;
  57.   d = q->top;
  58.   key = d->key;
  59.   if (q->top == q->rear) {
  60.     q->top = NULL;
  61.     q->rear = NULL;
  62.   } else {
  63.     q->top = d->next;
  64.   }
  65.   free(d);
  66.   return key;
  67. }
  68.  
  69. void print_queue_list(struct queue q) {
  70.   while(q.top != NULL) {
  71.     printf("%c\n", q.top->key);
  72.     q.top = q.top->next;
  73.   }
  74. }
Runtime error #stdin #stdout 0.01s 1852KB
comments (?)
stdin
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Standard input is empty
stdout
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a

a
b

b
https://ideone.com/VLRFP
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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