Conditional Chaining

We can use the else if keyword to define an additional condition that will be evaluated in case the previous condition is not met:

index


              12345678910
            
package main
import "fmt"

func main() {
    if (3 > 4) {
        fmt.Println("3 is greater than 4")
    } else if (3 > 2) {
        fmt.Println("3 is greater than 2")
    }
}

In the above program, the expression 3 > 4 is checked first, which is false; hence the program proceeds to the next statement (3 > 2) defined using the else if keyword. The next condition is true, so the output displays the result of the second Println statement.

We can add as many additional conditions as needed using else if statements:

index


              1234567891011121314
            
package main
import "fmt"

func main() {
    if (3 > 4) {
        fmt.Println("3 is greater than 4")
    } else if (3 > 3) {
        fmt.Println("3 is greater than 3")
    } else if (3 > 2) {
        fmt.Println("3 is greater than 2")
    } else if (3 > 1) {
        fmt.Println("3 is greater than 1")
    }
}

It's important to note that the above program only outputs 3 is greater than 2, even though the next condition is also true. This demonstrates that an if-else if chain stops evaluating conditions as soon as it encounters a true condition.

This process is referred to as conditional chaining because we are essentially defining conditions in a chain using if-else if keywords.

Note

In a conditional chain, only one code block is executed, the one that satisfies the condition, while the rest are skipped.

Alternatively, instead of chaining conditionals using the if-else if combination, we can write each condition using separate if statements. However, this approach produces a different output because it's no longer a single chain; it's a set of separate conditions, and therefore, it won't stop executing if one or more of the conditions are met:

index


              1234567891011121314151617
            
package main
import "fmt"

func main() {
    if (3 > 4) {
        fmt.Println("3 is greater than 4")
    }
    if (3 > 3) {
        fmt.Println("3 is greater than 3")
    }
    if (3 > 2) {
        fmt.Println("3 is greater than 2")
    }
    if (3 > 1) {
        fmt.Println("3 is greater than 1")
    }
}

Up to this point, for the sake of simplicity, we have been using values in boolean expressions. However, it is more common to use variables or a combination of variables and values in boolean expressions:

index


              123456789
            
package main
import "fmt"

func main() {
    var value int = 10
    if (value == 10) {
        fmt.Println("The variable has the expected value.")
    }
}

In a conditional chain, we can use the else keyword to indicate a code block that should be executed if none of the conditions in the chain are met:

index


              12345678910111213
            
package main
import "fmt"

func main() {
    var value int = 70
    if (value < 50) {
        fmt.Println("The value is less than 50")
    } else if (value == 50) {
        fmt.Println("The value is equal to 50")
    } else {
        fmt.Println("The value is greater than 50")
    }
}

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Seção 3. Capítulo 3