Generic Delegates 泛型委派
Delegate 委派
- 為什麼要使用委派？ 將一個方法作為參數傳遞給另一個方法
- 委派概念 聲明一個委派類型
委派所指向的函數必須跟委具有相同的簽名 - 匿名函數 沒有名字的函數
一般求數組的最大值寫法
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
public static int GetMax(int[] nums) { //整數陣列求最大值
int max = nums[0];
for (int i = 0; i < nums.Length; i++) {
if (max < nums[i]) max = nums[i];
}
return max;
}
public static string GetMax(string[] nums) { //字串陣列求最大值
string max = nums[0];
for (int i = 0; i < nums.Length; i++) {
if (max.Length < nums[i.Length max = nums[i];
}
return max;
}
練習：使用委派求數組的最大值
這兩個函數有什麼差別？
是不是都可以把類型改成object
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
namespace 求數組的最大值
{
public delegate int DelCompare(object o1, object o2);
internal class Program
{
static void Main(string[] args)
{
object[] o = { "ass", "wesfd", "dfasfsdfds", "fsafdsd" };//{ 1, 2, 3, 4, 5 };
object result = GetMax(o, Compare2); //Compare);
Console.WriteLine(result);
Console.ReadKey();
}
public static object GetMax(object[] nums, DelCompare del)
{
object max = nums[0];
for (int i = 0; i < nums.Length; i++)
{
//要傳一個比較的方法
//max-nums[i]<0,說明max是小於nums[i]，就要交換
if (del(max, nums[i]) < 0)
{
max = nums[i];
}
}
return max;
}
//o1指的是max, o2指的是nums[i]
public static int Compare(object o1, object o2) //整數陣列
{
int n1 = (int)o1;
int n2 = (int)o2;
return n1 - n2;
}
public static int Compare2(object o1, object o2) //字串陣列
{
string s1 = (string)o1;
string s2 = (string)o2;
return s1.Length - s2.Length;
}
//public static object GetMax(string[] nums)
//{
// string max = nums[0];
// for (int i = 0; i < nums.Length; i++)
// {
// //if (max.Length < nums[i.Length max = nums[i];
// max = max.Length > nums[i].Length ? max : nums[i];
// }
// return max;
//}
}
}
寫成匿名函數
1
2
3
4
5
6
//寫成匿名函數
object result = GetMax(o, delegate (object o1, object o2) {
string s1 = (string)o1;
string s2 = (string)o2;
return s1.Length - s2.Length;
});
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
namespace 求數組的最大值
{
public delegate int DelCompare(object o1, object o2);
internal class Program
{
static void Main(string[] args)
{
object[] o = { "ass", "wesfd", "Adfasfsdfds", "fsafdsd" };//{ 1, 2, 3, 4, 5 };
//object result = GetMax(o, Compare2);
//寫成匿名函數
object result = GetMax(o, delegate (object o1, object o2) {
string s1 = (string)o1;
string s2 = (string)o2;
return s1.Length - s2.Length;
});
Console.WriteLine(result);
Console.ReadKey();
}
public static object GetMax(object[] nums, DelCompare del)
{
object max = nums[0];
for (int i = 0; i < nums.Length; i++)
{
//要傳一個比較的方法
//max-nums[i]<0,說明max是小於nums[i]，就要交換
if (del(max, nums[i]) < 0)
{
max = nums[i];
}
}
return max;
}
//o1指的是max, o2指的是nums[i]
//public static int Compare(object o1, object o2) {
// int n1 = (int)o1;
// int n2 = (int)o2;
// return n1 - n2;
//}
//public static int Compare2(object o1, object o2) {
// string s1 = (string)o1;
// string s2 = (string)o2;
// return s1.Length - s2.Length;
//}
//public static object GetMax(string[] nums)
//{
// string max = nums[0];
// for (int i = 0; i < nums.Length; i++)
// {
// //if (max.Length < nums[i.Length max = nums[i];
// max = max.Length > nums[i].Length ? max : nums[i];
// }
// return max;
//}
}
}
寫成 Lamda表達式
1
2
3
4
5
6
//寫成Lamda表達式
object result = GetMax(o, (object o1,object o2) => {
string s1 = (string)o1;
string s2 = (string)o2;
return s1.Length - s2.Length;
});
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
namespace 求數組的最大值
{
public delegate int DelCompare(object o1, object o2);
internal class Program
{
static void Main(string[] args)
{
object[] o = { "ass", "wesfd", "Adfasfsdfds", "fsafdsd" };//{ 1, 2, 3, 4, 5 };
//object result = GetMax(o, Compare2);
//寫成匿名函數
//object result = GetMax(o, delegate (object o1, object o2) {
// string s1 = (string)o1;
// string s2 = (string)o2;
// return s1.Length - s2.Length;
//});
//寫成Lamda表達式
object result = GetMax(o, (object o1,object o2) => {
string s1 = (string)o1;
string s2 = (string)o2;
return s1.Length - s2.Length;
});
Console.WriteLine(result);
Console.ReadKey();
}
public static object GetMax(object[] nums, DelCompare del)
{
object max = nums[0];
for (int i = 0; i < nums.Length; i++)
{
//要傳一個比較的方法
//max-nums[i]<0,說明max是小於nums[i]，就要交換
if (del(max, nums[i]) < 0)
{
max = nums[i];
}
}
return max;
}
//o1指的是max, o2指的是nums[i]
//public static int Compare(object o1, object o2) {
// int n1 = (int)o1;
// int n2 = (int)o2;
// return n1 - n2;
//}
//public static int Compare2(object o1, object o2) {
// string s1 = (string)o1;
// string s2 = (string)o2;
// return s1.Length - s2.Length;
//}
//public static object GetMax(string[] nums)
//{
// string max = nums[0];
// for (int i = 0; i < nums.Length; i++)
// {
// //if (max.Length < nums[i.Length max = nums[i];
// max = max.Length > nums[i].Length ? max : nums[i];
// }
// return max;
//}
}
}
這樣寫也很囉嗦，而且有用到object就會牽扯到拆箱&裝箱
練習：使用委派求任意數組的最大值
泛型委派 寫法
任意類型數組
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
namespace 泛型委派
{
public delegate int DelCompare<T>(T t1, T t2); //T type
//public delegate int DelCompare(object o1, object o2);
internal class Program
{
static void Main(string[] args)
{
//泛型委派 寫法
//求整數陣列最大值
int[] nums = { 1, 2, 3, 4, 5 };
int max = GetMax<int>(nums, Compare1);
Console.WriteLine(max);
//求字串陣列最大值(泛型委派+Lamda表達式)
string[] names = { "asdf", "sdf", "WERWxx" };
string max1 = GetMax<string>(names, (string s1, string s2) => {
return s1.Length - s2.Length;
});
Console.WriteLine(max1);
Console.ReadKey();
}
public static T GetMax<T>(T[] nums, DelCompare<T> del)
{
T max = nums[0];
for (int i = 0; i < nums.Length; i++)
{
//要傳一個比較的方法
//max-nums[i]<0,說明max是小於nums[i]，就要交換
if (del(max, nums[i]) < 0)
{
max = nums[i];
}
}
return max;
}
public static int Compare1(int n1, int n2)
{
return n1 - n2;
}
}
}