二分查找【c语言】
#include <stdio.h>int halfSearch( int arr[], int num, int size ) {int min = 0, max = ( size - 1), mid;if ( size == 0 ) { return -1; }while ( 1 ) {// 1. when the boundary is "min" or "max"if ( num == arr[ min ] ) { return min ; }if ( num == arr[ max ] ) { return max ; }// 2. check the not found.if ( 1 == ( max - min ) ) { return -1; }// 3. reset the middle.mid = ( max - min ) / 2 + min;// 4. check num is middle, and reset the boundary "min" or "max"if ( num == arr[ mid ] ) { return mid; }else if ( num > arr[ mid ] ) {min = mid;} else {max = mid;}}return -1;}void main(void) {int arr[] = {1,3,4,6,7,8,8,9,44,345,666}; // int idx = halfSearch( arr, 9 , sizeof( arr ) / sizeof( int ) );if ( idx == -1 ) {printf( "未找到！\n" );} else {printf( "找到数据%d,下标%d \n", arr[idx], idx );}}