更換按鈕位置

Question

l我的C＃winform項目有問題。

在我的項目中，我有一個功能，可以將按鈕的位置切換到原來的位置，如果它們在同一個區域。

私人無效myText_MouseUp（對象發件人，發送MouseEventArgs E） {

Point q = new Point(0, 0); 
     Point q2 = new Point(0, 0); 
     bool flag = false; 
     int r = 0; 
     foreach (Control p in this.Controls) 
     { 
      for (int i = 0; i < counter; i++) 
      { 
       if (flag) 
       { 
        if (p.Location.X == locationx[i] && p.Location.Y == locationy[i]) 
        { 
         oldx = e.X; 
         oldy = e.Y; 
         flag = true; 
         r = i; 
        } 
       } 
      } 
     } 
     foreach (Control p in this.Controls) 
     { 
      for (int j = 0; j < counter; j++) 
      { 
       if ((locationx[j] == p.Location.X) && (locationy[j] == p.Location.Y)) 
       { 
        Point arrr = new Point(oldx, oldy); 
        buttons[j].Location = arrr; 
        buttons[r].Location = new Point(locationx[j], locationy[j]); 
       } 
      } 
     } 
} 
    The problem with this code is that if they are in the same area, the buttons do not switch their locations. Instead they goes to the last button location. 

如果有人可以幫助我，這將幫助我很多:)

Answer 1

的if語句總是判斷爲真。這意味着，最終j循環會做到這一點：

// last time round the i loop, i == counter-1 
// and q == new Point(locationx[counter-1], locationy[counter-1]) 
for (int j = 0; j < counter; j++) 
{ 
    Point q2 = new Point(locationx[j], locationy[j]); 
    buttons[i].Location = q2; 
    buttons[j].Location = q; 
} 

這樣做的最終結果是，每一個按鈕的Location設置爲q，這是

new Point(locationx[counter-1], locationy[counter-1]) 

---

爲什麼會出現if聲明始終評估爲true。那麼，首先讓我們來看看一對夫婦的or條款在if聲明：

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X == q2.X)) 

這相當於

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 

含==測試線路已最終完全沒有影響條件的結果。實際上所有包含==的行都可以進行類似的處理。這使得：

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X <= q2.X)) 

我們可以凝聚

|| ((q.Y >= q2.Y) && (q.X <= q2.X)) 
|| ((q.Y >= q2.Y) && (q.X >= q2.X)) 

到

|| ((q.Y >= q2.Y) 

，同樣

|| ((q.Y <= q2.Y) && (q.X >= q2.X)) 
|| ((q.Y <= q2.Y) && (q.X <= q2.X)) 

相同

|| ((q.Y <= q2.Y) 

結合

|| ((q.Y >= q2.Y) 
|| ((q.Y <= q2.Y) 

，你可以看到if條件始終計算爲true。