Strings

Introduction

Strings are a sequence of UTF-8 characters (the 1-byte ASCII-code is used when possible, and a 2-4 byte UTF-8 code when necessary). UTF-8 is the most widely used encoding. It is the standard encoding for text files, XML files, and JSON strings. With string data type, you can reserve 4 bytes for characters, but Go is intelligent enough that it will reserve one-byte if the string is only an ASCII character.

Strings in Go

Contrary to strings in other languages as C++, Java or Python that are fixed-width (Java always uses 2 bytes), a Go string is a sequence of variable-width characters (each 1 to 4 bytes).

Advantages of strings

The advantages of strings are:

• Go strings and text files occupy less memory/disk space (because of variable-width characters).
• Since UTF-8 is the standard, Go doesn’t need to encode and decode strings like other languages have to do.

Strings are value types and immutable, which means that once created, you cannot modify the contents of the string. In other words, strings are immutable arrays of bytes.

Types of string literals

Two kinds of string literals exist:

• Interpreted strings
• Raw strings

Interpreted strings

They are surrounded by " " (double quotes). For example, escape sequences are interpreted:

"\n" // represents a newline
"\r" // represents a carriage return
"\t" // represents a tab
"\u" // represents Unicode characters
"\U" // also represents Unicode characters

Raw strings

They are surrounded by back quotes `` and are not interpreted. For example in the following string:

`This is a raw string \n`

\n is not interpreted but taken literally. They can span multiple lines.

Length of a string

Strings in Go do not terminate by a special character as in C/C++. The initial (default) value of a string is the empty string “”. The usual comparison operators (==, !=, <, <=, >=, and >) work on strings by comparing byte by byte in memory.

The length of a string str (the number of bytes) is given by the len() function:

len(str)

The contents of a string (the raw bytes) are accessible via standard indexing methods, the index is written between [], with the index starting from 0. The following illustration shows indexing of a string of length 5: