Strings in Go

[Harald Schlindwein]

Hi,


in Java it is a known problem to change strings at runtime especially in loops and very often.
That lead to StringBuilder/Buffer.

How does Go handle that problem or is there any for Go at all?

Given
var s string = "Some text"
var t string = "Some text"
would mean at runtime s == t in Java (afaik)
Also in Go? Because the byte field is the same and the compiler could/should know it...

Harald

[Mark Summerfield]

Hi Harald,

In Go, strings are immutable just as they are in Java and Python. This has many benefits both in terms of performance and for writing robust concurrent programs.

Given
var s string = "Some text"
var t string = "Some text"
would mean at runtime s == t in Java (afaik)

This is an implementation detail that may or may not be true for any given JVM. The same applies in Python. In Go, s == t is true (== sensibly does the string comparison), but &s != &t (i.e., each has a different address so each string is unique). However, the address uniqueness is still just an implementation detail and shouldn't be assumed.

Go's equivalent to Java's StringBuilder is bytes.Buffer:

var buffer bytes.Buffer
for {
    s := readStringFromSomewhere()
    if len(s) {
        buffer.WriteString(s)
    } else {
        break
    }
}
fmt.Print(buffer.String(), "\n")

This assumes you have some readStringFromSomewhere() function that returns an empty string when it is finished. A slightly more sophisticated example is shown in "Programming in Go" on page 88.