Comparison of three cycles

 

Switch-case

Syntax:

Switch (expression/variable)

{

Case value 1: Statement 1;

Break;

Case value 2: Statement 2;

Break;

Default: Statement 3

Break;

.............................

}

 

Execution Process

 

WhenProgramRun switch (expression/variable) to judge the expression in brackets first,

 

Execute the value 1 after case in braces: If the value matches 1, execute Statement 1,

Run break, jump out of the switch, and then executeCode

If the value 1 does not match, start to judge the value 2,

Match or not. If yes, Statement 2 is executed and break is executed. The switch is jumped out,

If none of them match, run the code after default and then break.

 

 

While Loop

 

 

Syntax:

 

Int I = 0;

While (condition/expression) --------------------------------- à I <a certain number

{

Loop body;

I ++;

}

 

Execution Process:

 

When running the while (condition) program, you must first determine whether the condition is true.

If true is true, the loop body is executed if false is not true,

And I ++ (I value plus 1)

If not, skip the code after the loop execution.

 

While, you must first determine whether the condition is true and then execute the loop body,

Do-while first executes the loop body and then judges

 

While loop example:

 

 

Do

{

Loop body;

} While (condition );

Execution Process:

 

When the program runs to do, it directly enters the loop body;

Then, go to the while (condition) line of code to determine.

If the condition is true, execute the loop body again,

Otherwise, jump out of the loop and execute the subsequent code;

 

At least one loop body is executed, (Do-while)

It is possible that when the initial value of the loop body (while) does not meet the conditions

 

 

Do-while first executes the loop body and then judges

While, you must first determine whether the condition is true and then execute the loop body,

 

Example of do-while:

 

 

Comparison between a while loop and a do-while loop

 

 

 

For Loop

 

For (expression 1; expression 2; expression 3)

{

Loop body;

}

 

Execution Process:

 

 

When the program runs for (expression 1; expression 2; expression 3)

This line of code

 

First run to: expression 1

Run expression 2 again

 

The loop body in the execution;

Execution expression 3;

Execute expression 2 again

Then execute the loop body;

 

For Loop Example 1:

 

 

 

For Loop Example 2: (you can use F11 for step-by-step testing)

 

 

Comparison of while and for loops: