InsertSort

void insertSort(int num[] , int length)  
{  
	
    for(int i=2 ; i<length ; i++)    // We need to start to sort from num[2], because num[0] is the guard.  
    {                               // and num[1] is the first sorted value.  
        num[0] = num[i] ;           // num[0] is the guard which is the value that will be inserted, num[i] ;  
        int j = i ;  
        while(num[0]<num[j-1])       // We needn't to worry about the ArrayIndex out of bounds,  
        {                           // because the first number of array is num[0] that equals  
            num[j] = num[j-1] ;     // of num[i].  
            j-- ;  
        }  
        num[j] = num[0] ;  
    }  	
}