How to use conditional statements in Go?

In Go, conditional statements are one of the keys to controlling program flow. When writing code, we often need to use conditional statements to implement specific logic control. In this article, we will discuss how to use conditional statements in Go language.

1. If statement

The if statement is one of the most common conditional statements in Go. It determines whether to execute a block of code based on the value of a Boolean expression. The following is the basic syntax structure of the if statement:

if condition {
   //if block of code
}

Among them, condition is a Boolean expression, which can be any expression that returns a Boolean value. When this expression evaluates to true, the code in the if statement is executed. For example:

if x > 10 {
   fmt.Println("x is greater than 10")
}

In this example, if the value of x is greater than 10, "x is greater than 10" will be output.

Of course, you can also add an else clause in the if statement. This code will execute the condition in the if block if the condition is not met:

if condition {
   //if block of code
} else {
   //else block of code
}

For example:

if x > 10 {
   fmt.Println("x is greater than 10")
} else {
   fmt.Println("x is less than or equal to 10")
}

This In the example, if the value of x is greater than 10, "x is greater than 10" will be output, otherwise "x is less than or equal to 10" will be output.

In addition to if and else, you can also add an else if statement to handle more situations:

if condition1 {
   //if block of code
} else if condition2 {
   //else if block of code
} else {
   //else block of code
}

For example:

if x > 10 {
   fmt.Println("x is greater than 10")
} else if x > 5 {
   fmt.Println("x is greater than 5 and less than or equal to 10")
} else {
   fmt.Println("x is less than or equal to 5")
}

In this example, if x If the value is greater than 10, "x is greater than 10" will be output. If the value of x is greater than 5 and less than or equal to 10, "x is greater than 5 and less than or equal to 10" will be output. Otherwise, "x is less than or equal to 5”.

2. Switch statement

Compared with the if statement, the switch statement is more logical and readable. In Go, a switch statement consists of multiple case blocks and an optional default block. When the conditions of a certain case are met, the corresponding code block will be executed. The following is the basic syntax structure of the switch statement:

switch expression {
   case value1:
      //case 1 block of code
   case value2:
      //case 2 block of code
   ...
   case valueN:
      //case N block of code
   default:
      //default block of code
}

Among them, expression is an expression to be checked, which can be any type of expression. value1, value2,..., valueN are the values ​​to be checked. If the value of expression is equal to a certain value, the matching code block will be executed; if the value of expression is not equal to any value, the default block will be executed.

For example:

switch day {
   case 1:
      fmt.Println("Monday")
   case 2:
      fmt.Println("Tuesday")
   case 3:
      fmt.Println("Wednesday")
   case 4:
      fmt.Println("Thursday")
   case 5:
      fmt.Println("Friday")
   case 6:
      fmt.Println("Saturday")
   case 7:
      fmt.Println("Sunday")
   default:
      fmt.Println("Invalid day")
}

In this example, if the value of day is 1, then "Monday" is output, if the value of day is 2, then "Tuesday" is output, and so on. If no case matches the value of day, "Invalid day" is output.

3. Select statement

The Select statement is a special statement in Go that is used to handle channel communication. At any time, you can use select to wait for multiple channel operations. It blocks until one of the channels returns data. The following is the basic syntax structure of the select statement:

select {
   case communication1:
      //communication1 block of code
   case communication2:
      //communication2 block of code
   ...
   case communicationN:
      //communicationN block of code
   default:
      //default block of code
}

Among them, communication1, communication2,..., communicationN are the channel operations to be performed. When any of the channels returns data, the corresponding code block will be executed. If no data is returned from any channel, the default block is executed.

For example:

select {
   case <- channel1:
      fmt.Println("Received from channel1")
   case <- channel2:
      fmt.Println("Received from channel2")
   default:
      fmt.Println("No data received")
}

In this example, if channel1 returns data, then output "Received from channel1", if channel2 returns data, then output "Received from channel2", if not If any channel returns data, "No data received" will be output.

Summary

Conditional statements in Go include if statements, switch statements and select statements. The if statement determines whether to execute the code block based on a Boolean expression. Else and else if clauses can be added as needed. The switch statement executes the corresponding code block based on the value of the expression, including multiple case blocks and an optional default block. The select statement is used to handle channel communication. At any time, you can use select to wait for multiple channel operations. These conditional statements can help us implement complex logic control and improve the readability and maintainability of the code.

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