Beginning-Cpp-Programming-Section-09/80_switch_case_statement.txt at main · SystemsScientist/Beginning-Cpp-Programming-Section-09 · GitHub

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
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

Section 09: switch-case Statement
----------------------------------------------------------------------

The switch statement I

	switch (integer_control_expr) {
		case expression_1:
			statement_1;
			break;
		case expression_2:
			statement_2;
			break;
		case expression_3:
			statement_3;
			break;
		...

		case expression_n:
			statement_n;
			break;
		default:
			statement_default;
	}


Example 1

	switch (selection) {
		case '1': cout << "1 selected";
			  break;
		case '2': cout << "2 selected";
			  break;
		case '3':
		case '4': cout << "3 or 4 selected";
			  break;
		default: cout << "1, 2, 3, 4 NOT selected";
	}


fall-through Example

	switch (selection) {
		case '1': cout << "1 selected";

		case '2': cout << "2 selected";

		case '3': cout << "3 selected";

		case '4': cout << "4 selected";
			  break;
		default: cout << "1, 2, 3, 4 NOT selected";
	}


with an enumeration

	enum Color {
		red, green, blue
	};
	Color screen_color {green};

	switch (screen_color) {
		case red:   cout << "red"; break;
		case green: cout << "green"; break;
		case blue:  cout << "blue"; break;
		default:    cout << "should never execute";
	}


The switch Statement II

	- The control expression must evaluate to an integer
	  type

	- The case expressions must be constant expressions
	  that evaluate to integer or integers literals

	- Once a match occurs, all following case sections
	  execute UNTIL a 'break' has reached the switch
	  complete

	- Best practice - provide a break statement for
	  each case

	- Best practice - 'default' is optional, but should
	  be handled