如何纠正循环阵列插入索引

我正在尝试在动态循环数组中找到插入前端的公式。我遇到的一个问题是当尝试运行显示时，在这种情况下，前两次插入后的inx将因为没有被占用的索引而关闭。这是假设我正在按照正确的方式选择开始索引。如何纠正循环阵列插入索引

void insertCDAfront(CDA *items,void *val){//insert in the slot prior t   
    assert(items->array!=0); 
    if(sizeCDA(items)==0){ 
     items->array[items->start]=val; 
     items->size++; 

    } 
    else{ 

     if(items->size==items->capacity){ 
      items->capacity=items->capacity*items->factor; 
      void **arr=calloc(items->capacity,sizeof(void *)); 
      assert(arr!=0); 
      for(int i=0;i<items->size;i++){ 
       arr[i]=getCDA(items,i); 

      } 
      items->array=arr; 
      items->start=0; 

     } 

     items->start=(items->start-1+items->capacity)%items->capacity; 
     items->array[items->start]=val; 
     items->start=0; 

     items->size++; 
    } 
} 


void *getCDA(CDA *items,int index){// 
    assert (index<items->size&&index>=0); 
    int spot=(items->start+index+items->capacity)%items->capacity; 
    return items->array[spot]; 
} 

void displayCDA(FILE *f,CDA *items){ 
    int i=0; 
    if (items->size==0){ 
     fprintf(f,"("")"); 
    } 
    else if (items->size==1){ 
     fprintf(f,"("); 
     items->display(f,items->array[i]); 
     fprintf(f,")"); 
    } 
    else{ 
     fprintf(f,"%s","("); 
     while (i!=items->size-1){  //i!=end 
      items->display(f,getCDA(items,i)); 
      fprintf(f,"%s",","); 
      i++; 
     } 

     items->display(f,getCDA(items,i)); 
     fprintf(f,"%s",")"); 
    } 
}

来源

2017-09-14 mokarab

' “（” “），”'应该只是' “（）”' – Barmar

'size == 1'和'size> 1'不需要单独的情况。具有'while'循环的版本在两种情况下都可以工作。 – Barmar

听起来像你想做一个环形缓冲区......这里是一个学术起点：

#define PREDETERMINED_ERROR_VALUE (0) 
#define MAX_SIZE     (100) 
int ring_buffer[MAX_SIZE] = {0}; 
unsigned int head = 0; 
unsigned int tail = 0; 

void add_item(int new_data) 
//!\todo check for overrun 
{ring_buffer[head++] = new_data;} 

unsigned int get_size_of_ring_buffer(void) 
{ 
unsigned int ret; 
if tail <= head 
    ret = head - tail; 
else 
    ret = head + MAX_SIZE - tail; 
return (ret); 
} 

int get_item(void) 
{ 
//!\todo consider returning error code and modifying a param with the data 
int ret; 
if (tail != head) 
    ret = ring_buffer[tail++]; 
else 
    ret = PREDETERMINED_ERROR_VALUE; 
return (ret); 
}

来源

2017-09-14 15:58:58 grambo

如何纠正循环阵列插入索引

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