//Data為要查找的數組，x為待查找數據值，beg為查找范圍起始，last為查找范圍終止 
//非遞歸法 
int BiSearch(int data[], const int x, int beg, int last) 
{ 
    int mid;//中間位置 
    if (beg > last) 
    { 
        return -1; 
    } 
    while(beg <= last) 
    { 
        mid = (beg + last) / 2; 
        if (x == data[mid] ) 
        { 
            return mid; 
        } 
        else if (data[mid] < x) 
        { 
            beg = mid + 1; 
        } 
        else if (data[mid] > x) 
        { 
            last = mid - 1; 
        } 
    } 
    return -1; 
} 
//遞歸法 
int IterBiSearch(int data[], const int x, int beg, int last) 
{ 
    int mid = -1; 
    mid = (beg + last) / 2; 
    if (x == data[mid]) 
    { 
        return mid; 
    } 
    else if (x < data[mid]) 
    { 
        return IterBiSearch(data, x, beg, mid - 1); 
    } 
    else if (x > data[mid]) 
    { 
        return IterBiSearch(data, x, mid + 1, last); 
    } 
    return -1; 
} 
//主函數 
int _tmain(int argc, _TCHAR* argv[]) 
{ 
    int data1[60] = {0}; 
    int no2search = 45; 
    cout << "The array is : " << endl; 
    int siz = sizeof(data1)/sizeof(int); 
    for (int i = 0; i < siz; i++) 
    { 
        data1[i] = i; 
        cout << data1[i] << " "; 
    } 
    cout << endl; 
    int index = -1; 
    //index = BiSearch(data1, no2search, 0, siz); 
    index = IterBiSearch(data1, no2search, 0, siz); 
    cout << "Index of " << no2search << " is " << index << endl; 
    getchar(); 
    return 0; 
} 

/**
  * 折半查找字符在數組中的位置(有序列表)
  * @param array 被檢索的數組
  * @param x  要查找的字符
  * @returns 字符在數組中的位置，沒找到返回-1 
  */ 
function binarySearch(array,x){
  var lowPoint=1;                    
 var higPoint=array.length;
 var returnValue=-1;               
 var midPoint;
 var found=false;                  
 while ((lowPoint<=higPoint)&&(!found)){
  midPoint=Math.ceil((lowPoint+higPoint)/2);
  //console.log(lowPoint+"===="+midPoint+"===="+higPoint);
  if(x>array[midPoint-1]){
   lowPoint=midPoint+1;
  }
  else if(x<array[midPoint-1]){
   higPoint= midPoint-1;
  }
  else if(x=array[midPoint-1]){
   found=true;
  }
 }
 if(found){
    returnValue=midPoint;
 }
 return returnValue;
}
/*var array2=[1,2,3,4,5,6,7,8,9,100,109];*/
var array2=['a','b','c','d','e','f','g'];
console.log(binarySearch(array2,'c'));