# 類別中的函數成員相互呼叫

以[上一篇](/java-08/java-08-2.md)中的範例做示範與修改

```
class CRectangle {  //定義矩形類別
	//資料成員
	int width;  //寬
	int height; //長
	//函數成員
	int area(){   //計算面積
		System.out.println("面積＝ "+width*height);
		}
	int perimeter(){  //計算周長
		System.out.println("周長＝ "+2*(width+height);
		}
        int show_all(){  //在show_all 函數中 呼叫計算面積的函數與計算周長的函數
                System.out.println("寬＝ "+width+" ,長＝ "+height);
                area();  //呼叫計算面積的函數
                perimeter(); //呼叫計算周長的函數
                }

}
public class ch08_3 {

	public static void main(String[] args) {
		CRectangle book;   //宣告CRectangle類別的變數 book
		book= new CRectangle(); //建立物件

		book.width=10;  //給寬一個值
		book.height=5;  //給長一個值
		book.show_all(); //呼叫show_all()
	}
}
```

輸出結果：\
寬＝ 10 ,長＝ 5\
面積＝ 50\
面積＝ 30

在類別中函數成員的程式碼敘述當中，直接加上類別中其他函數成員的函數名稱即可呼叫。


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