Swift 2.0 Learning Note (Day 18)-How many branch statements?

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Branch statements are also called conditional statements, and the SWIFT programming language provides three branch statements of if, switch, and guard.

if Statement

The choice structure guided by the IF statement has the IF structure, the IF-ELSE structure and the ELSE-IF structure 3 kinds.

The example code for the If structure is as follows:

var score = 95

If score >= 85 {

Print ("You're excellent!") ")

}

The results of the program run as follows:

You are so good!

The sample code for the IF-ELSE structure is as follows:

var score = 95

If score < 60 {

Print ("Failed")

} else {

Print ("Pass")

}

The results of the program run as follows:

Pass

The sample code for the ELSE-IF structure is as follows:

Let Testscore = 76

var grade:character

If Testscore >= 90 {

Grade = "A"

} else if Testscore >= 80 {

Grade = "B"

} else if Testscore >= 70 {

Grade = "C"

} else if Testscore >= 60 {

Grade = "D"

} else {

Grade = "F"

}

Print ("Grade = \ (Grade)")

The output results are as follows:

Grade = C

Switch Statement

The switch statement is also called a toggle statement, which provides a multi-branch program structure.

The example code for the basic form of the switch statement is as follows:

Let Testscore = 86

var grade:character

Switch TESTSCORE/10 {

Case 9:

Grade = "excellent"

Case 8:

Grade = "Liang"

Case 7, 6:

Grade = "Medium"

Default

Grade = "Poor"

}

Print ("Grade = \ (Grade)")

The output results are as follows:

Grade = Benign

Guard Statement

The Guard statement is a newly added keyword for Swift 2.0, which is very similar to the IF statement and is designed to improve the readability of the program.

The guard statement must have an else statement with the following syntax:

Guard conditional expression-else {

Jump statement

}

Statement Group

When the conditional expression is true, skips the contents of the Else statement and executes the statement group contents. The conditional expression is false when the content in the Else statement is executed, and the jump statement is typically return, break, continue, and throw.

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Swift 2.0 Learning Note (Day 18)-How many branch statements?