Program Design Basics Chapter fifth programming of selection structure (knowledge point)

The fifth chapter design of the selection structure

The first part:

Summarize

1 A program structure that uses different program segments to process a certain condition is called a selection structure.

2 C-language selection statements include if and switch statements

3 Use the break statement to interrupt the execution of the switch statement.

4 using the goto statement, the program execution process can be unconditionally specific.

Part II:

Separate description

5.1 Select Structure program with IF statement design

5.1.1 a simple if statement

Conditions of use: meet the conditions on the execution, not satisfied will not be executed.

Format:

If (expression) {statement 1}

5.1.2 If_else Statements

Format:

If (expression 1) {Statement 1}

(Expression 2) {Statement 2}

5.1.3 Nested IF statements

Form 1:if (expression 1)

If (expression 2) statement 1

Else Statement 2

Else Statement 3

Form 2:if (expression 1) {

if (expression 2) statement 1

}else Statement 2

Form 3:if (expression 1) Statement 1

else if (expression 2) Statement 2

Else Statement 3

5.2 Designing a multi-branch structure program with switch statements

5.2.1switch statements

Format:

switch (expression)

case constant Expression 1: statement 1 (break;)

Case constant Expression 2: statement 2 (break;)

Case constant Expression 3: statement 3 (break;)

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

case constant Expression N: statement n (break;)

Default: Statement n+1

5.2.3 Nested SWITCH statements

5.3 Unconditional Turn statement (GOTO)

Format:

S

Goto S;

Add:

1: Digit: g=n%10

2:10-bit: s=n/10%10

3: Hundred: b=n/100%10

4: Thousand: q=n/1000%10

Program Design Basics Chapter fifth programming of selection structure (knowledge point)