binarysearch.c

从键盘输入一段字符

/*折半查找*/
#include<stdio.h>

void sort(int num[]); 
int main()                      //折半查找：查找给定字母出现的次数
{
	
    
    int x,low,high,mid;
    int num[10] = {1,3,6,2,34,5,6,22,67,11};
    sort(num);                           //首先从小到大排序 
    low = 0;
    high = 9;
    
    printf("请输入要查询的数字\n");
    scanf("%d",&x);
    while(low <= high)
    {
        mid = (low + high)/2;
        if(x == num[mid])
         break;
        else if(x < num[mid]) 
         high = mid - 1;
        else
         low = mid + 1;
              
    }
    if(low > high)
     printf("Not found\n");
    else 
      printf("The position in the array is: %d\n",mid+1);
     
    scanf("%d",&low);
    return 0;
   
  
}

void sort(int num[])                         //选择排序（冒泡排序）：按照出现次数由高到低进行排序，按顺序输出，并保存到文件中
{

	int i,j,n,pos,temp;
	
	for(i = 0;i<10-1;i++)
	 {
	 	pos = i;
	 	for(j = i + 1;j < 10;j++)
	 		if(num[j] < num[pos])
	 			pos = j;
	 	if(pos != i)
	 		{
	 			temp = num[i];
	 			num[i] = num[pos];
	 			num[pos] = temp;
	 		
	 			}	
	 
	 	}
 		//按顺序输出
	 	printf("after orderd, the result is:\n");
         for(i = 0;i < 10;i++)
	  	    printf("%d\n",num[i]);

}