Go Programming: What's the Difference Between `:=` and `=`?

Exploring the Difference Between := and = in Go

As a novice in Go programming, you may encounter the usage of both := and = operators, leaving you wondering about their similarities and distinctions. While both can seemingly assign values, there are subtle nuances to consider.

Understanding the Role of =

= primarily functions as an assignment operator in Go. It assigns a specified value to a previously declared variable. For instance:

var name = "John Doe"

In this example, name is declared as a variable of type string, and the assignment operator assigns the value "John Doe" to it.

Diving into :=

:= is known as the short variable declaration syntax. It is primarily used to simultaneously declare and assign values to new variables. Consider the following:

a := 10
b := 20

In this instance, a and b are newly declared variables, and their types are inferred based on the assigned values. The type of a would be int, and b would be int as well.

Key的区别

The crucial difference between := and = lies in their usage. =: is essentially a declaration, while = is an assignment. This means that while := can introduce new variables and assign values to them, = only assigns values to existing variables.

Moreover, := may appear only within functions. It can be used to declare local temporary variables in constructs like if, for, or switch statements. In contrast, = is permitted in any context where an expression is allowed.

Additional Notes

To summarize, := serves as an abbreviation to simplify the common pattern of variable declaration and assignment in Go. In circumstances where new variables are being defined or values assigned to uninitialized variables, := is a convenient choice. However, for standard assignment purposes, = remains the appropriate operator.

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