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  1. #include <stdio.h>
  2. #define QUEUE_SIZE 5
  3. int queue[QUEUE_SIZE];
  4. int front = 0;  /* 先頭ポインタ */
  5. int rear = 0;   /* 末尾ポインタ */
  6.  
  7. int enQueue(int x){
  8.     printf("enQueue() front = %d rear = %d\n", front, rear);
  9.     if( ((rear+1) % QUEUE_SIZE) == front ){
  10.         return -1;
  11.     }
  12.     queue[rear] = x;
  13.     rear = (rear + 1) % QUEUE_SIZE;
  14.     return 1;
  15. }
  16.  
  17. int deQueue(){
  18.     printf("deQueue() front = %d rear = %d\n", front, rear);
  19.     if( front == rear ){
  20.         printf("deQueue() queue empty\n");
  21.         return -1;
  22.     }
  23.  
  24.     int x = queue[front];
  25.     front = (front + 1) % QUEUE_SIZE;
  26.     printf("deQueue: %d\n", x);
  27.     return x;
  28. }
  29.  
  30. void printQueue(void){
  31.     printf("printQueue: ");
  32.  
  33.     int i = front;
  34.     while(i != rear){
  35.         printf("%d ", queue[i]);
  36.         i = (i + 1) % QUEUE_SIZE;
  37.     }
  38.     printf("\n");
  39. }
  40.  
  41. int main() {
  42.  
  43.     enQueue(1);
  44.     enQueue(2);
  45.     enQueue(3);
  46.     printQueue();
  47.     deQueue();
  48.     deQueue();
  49.     deQueue();
  50.     printf("deQueue: %d\n", deQueue());
  51.  
  52.     return 0;
  53. }
Success #stdin #stdout 0s 5320KB
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stdin
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Standard input is empty
stdout
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enQueue() front = 0 rear = 0
enQueue() front = 0 rear = 1
enQueue() front = 0 rear = 2
printQueue: 1 2 3 
deQueue() front = 0 rear = 3
deQueue: 1
deQueue() front = 1 rear = 3
deQueue: 2
deQueue() front = 2 rear = 3
deQueue: 3
deQueue() front = 3 rear = 3
deQueue() queue empty
deQueue: -1
https://ideone.com/7IU0lP
language:
C (gcc 8.3)
created:
2 days ago
visibility:
public

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