折半查找

<pre name="code" class="cpp">#include<stdio.h>int main(){//折半查找函数声明int binSearch(int key,int *data,int dataSize);int binSearchByRecursive(int key,int *data,int head,int tail);int key;int position;//要查找的数在数据中的位置int dataSize=10;int data[10]={1,2,3,4,5,6,7,8,9,10};int i=0;for(;i<dataSize;i++){printf("%d  ",data[i]);}printf("\n调用普通折半查找函数,输入要查找的数字：");scanf("%d",&key);printf("\n");//调用折半查找函数position=binSearch(key,data,dataSize);if(position==-1){printf("没有找到\n");}else if(position==-2){printf("参数有误\n");}else{printf("找到数据：%d  ，数组下标%d\n",data[position],position);}printf("\n调用递归法折半查找函数,输入要查找的数字：");scanf("%d",&key);printf("\n");//调用折半查找递归法函数position=binSearchByRecursive(key,data,0,dataSize);if(position==-1){printf("没有找到\n");}else if(position==-2){printf("参数有误\n");}else{printf("找到数据：%d  ，数组下标%d\n",data[position],position);}}/**折半查找函数返回-1没有找到，-2参数有误，大于0表示位置*/int binSearch(int key,int *data,int dataSize){int head;int tail;int middle;if(&key==NULL||data==NULL||&dataSize==NULL){return -2;}head=0;tail=dataSize-1;middle=(head+tail)/2;//当不等于中间下标值时继续比较，一直到头下标和尾下标相等时退出比较//此时已全部比较完while(key!=data[middle]&&head!=tail){if(key>data[middle]){head=middle+1;}if(key<data[middle]){tail=middle-1;}middle=(head+tail)/2;}if(key==data[middle]) return middle;else return -1;}/**折半查找递归法*/int binSearchByRecursive(int key,int *data,int head,int tail){int middle;middle=(head+tail)/2;if(key==data[middle]){return middle;}if(head==tail){return -1;}if(key<data[middle]){return binSearchByRecursive(key,data,head,tail-1);}if(key>data[middle]){return binSearchByRecursive(key,data,head+1,tail);}}