Easy
tutorial for C / C ++ Control
statement 2 (switch case statements)
switch case statements:
-
As a conditional control statement, switch
case statements execute a specific execute statement when a specific
value is encountered.
- The structure of the switch case statement is as follows.
switch ('expression') {
case n1 : ' execute statement 1';
break;
break;
case n2 : ' execute statement 2';
break;
break;
case n3 : ' execute statement 3';
break;
break;
default: 'execute statement 0';
}
- If the value of 'expression' in the ' switch statement '
equals to n1, 'execute statement 1' is executed. The 'switch statement' ends by
a 'break' statement. That is, other execution statements are not executed.
-
When the value of 'expression' equals to n2, 'execute
statement 2' is executed. And the 'switch statement' ends by a 'break'
statement.
-
If the value of 'expression' is not n1, n2 or n3,
'execute statement 0' is executed.
- If there is no 'break' statement in the case statements, the ' switch statement ' does not exit
immediately, but executes the execute statements until it encounters the 'break'
statement or until it exits the switch statement.
Example Code
#include
<iostream>
using
namespace std;
int
main() {
int A, B;
A
= 3 ;
B
= 1 ;
switch(A){
case 1 : cout<<" A = 1 !
"<<endl ;
break;
case 2 : cout<<" A = 2 !
"<<endl ;
break;
case 3 : cout<<" A = 3 !
"<<endl ;
break;
default : cout<<" Wow"<<endl
;
}
switch(B){
case 1 : cout<<" B = 1 !
"<<endl ;
break;
case 2 : cout<<" B = 2 !
"<<endl ;
break;
case 3 : cout<<" B = 3 !
"<<endl ;
break;
default : cout<<" Wow
"<<endl ;
}
return 0;
}
results:
A
= 3 !
B
= 1 !
-
3 and 1 were assigned to integer type variables A and B, respectively.
-
Since the value of A in the first 'case' statement is 3, "A = 3 !"
corresponding to case 3 is printed.
-
In case of B, since the value is 1, "B = 1 !" is printed.
-
I will remove the break statement and execute above example.
Example Code
#include
<iostream>
using
namespace std;
int
main() {
int A, B;
A
= 3 ;
B
= 1 ;
switch(A){
case 1 : cout<<" A = 1 !
"<<endl ;
case 2 : cout<<" A = 2 !
"<<endl ;
case 3 : cout<<" A = 3 !
"<<endl ;
default : cout<<" Wow"<<endl
;
}
switch(B){
case 1 : cout<<" B = 1 !
"<<endl ;
case 2 : cout<<" B = 2 !
"<<endl ;
case 3 : cout<<" B = 3 !
"<<endl ;
default : cout<<" Wow
"<<endl ;
}
return 0;
}
results:
A = 3 !
Wow
B = 1 !
B = 2 !
B = 3 !
Wow
- If you remove the break statements in the previous
example and execute it, you get the above results.
- First, in case A, the value of A is 3, so "A = 3!" is printed.
- However, since there is no break statement, the following execute statement is
executed and thus "Wow" is printed.
- In case of B, the execution statement of case 1 is executed
and "b = 1!" is printed.
- However,
since there is no break statements, the remaining execution statements continue
to execute.
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