Go language function return value type inference mechanism

The function return value type in the Go language can be obtained through explicit declaration or compiler derivation. Derivation rules include: no explicit return is "void", a single return statement is the type of the return expression, and multiple return statements are the largest type of all return expressions. The inference mechanism simplifies code, improves readability, and facilitates correct use of the feature.

Go language function return value type derivation mechanism

Introduction

Go language , the return value type of a function can be obtained through explicit declaration or compiler derivation. Function return type inference is a powerful feature that simplifies code and improves readability.

Type derivation rules

The compiler deduce the return value type according to the following rules in the function body:

• If the function body does not return explicitly , then the return type deduced by the compiler is "void".
• If the function body has only one return statement, the compiler will deduce the return type as the type of the return expression.
• If the function body has multiple return statements, the compiler will deduce the return type as the largest type among all return expression types.

Practical cases

The following are several practical cases using type derivation:

Case 1: No explicit return

func add(x, y int) {
    return x + y
}

In this case, since there is no explicit return, the compiler will infer that the return value type is "void".

Case 2: Single return statement

func max(x, y int) int {
    if x > y {
        return x
    }
    return y
}

In this case, since the function has only one return statement, the compiler will infer that the return value type is int .

Case 3: Multiple return statements

func swap(x, y int) (int, int) {
    tmp := x
    x = y
    y = tmp
    return x, y
}

In this case, since the function has multiple return statements, the compiler will infer that the return value type is (int, int).

Conclusion

Function return value type deduction is a powerful feature in the Go language. It simplifies code and improves readability. It is important to fully understand the derivation rules to use this feature correctly.

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