golang strings can be seen as a collection of characters. A string can be of length 1 (one character), but its usually longer. A string is always written in double qoutes.

This means a string variable in golang can hold text: words, sentences, books

Programming languages have variables. These variables have a data type A variable can be of the data type string.

String example

String variable

In the example below we use golang to print text. First define a string variable, then output the variable with the function Printf(). Make sure you have the package "fmt" imported.

package main

import "fmt"

func main() {
   var str1 =  "This is a string variable!"
   fmt.Printf(str1)
}

Multiple lines

In Go programming, there are two ways to print multiple lines.

• Method 1. call display function Println x times,
• Method 2. use the newline character \n inside the string

Both of these are common in programming.

package main

import "fmt"

func main() {
   var str1 =  "This is a string variable!"

   // 1: function calls
   fmt.Println(str1)
   fmt.Println(str1)

   // 2: use newline character
   fmt.Printf("Hello World\nI am Go")  
}

This is a string variable!
This is a string variable!
Hello World
I am Go
Program exited.

Note: The zero value of type string is a string of zero length, that is an empty string "".

String index

The contents of the string (bytes) can be obtained by standard indexing, with an index written in parentheses [], and the index count from 0.

str[0]
str[i-1]
str[len(str)-1]

It is important to note that this conversion scheme is valid only for strings of pure ASCII codes (not Japanese, Chinese etc).

package main
import (
    "fmt"
)
func main() {
    s := "Go string example"
    for k, v := range s {
        fmt.Printf("k：%d,v：%c == %d\n", k, v, v)
    }
}

k：0,v：G == 71
k：1,v：o == 111
k：2,v：  == 32
k：3,v：s == 115
k：4,v：t == 116
k：5,v：r == 114
k：6,v：i == 105
k：7,v：n == 110
k：8,v：g == 103
k：9,v：  == 32
k：10,v：e == 101
k：11,v：x == 120
k：12,v：a == 97
k：13,v：m == 109
k：14,v：p == 112
k：15,v：l == 108
k：16,v：e == 101

Note Getting the address of a byte in the string is illegal, for example: &str [i].

The string of multiple lines in the code can be spliced in the following ways.

Direct-use operators

str := "Beginning of the string " + "second part of the string"

The operator += can also be used for strings:

s := "hel" + "lo, "
s += "world!"
fmt.Println(s)

The general comparison operators (==,!=, <, <=,>=, >) implement the comparison of strings by byte comparison in memory. You can get the byte length of the string by function len(), for example: len(str).

String join

To join strings, you can use the package strings which has the method .Join().

package main
import (
    "fmt"
    "strings"
)
func main() {
    s := strings.Join([]string{"hello", "world"}, ", ")
    fmt.Println(s)
}

hello, world

Program exited.

Print variables

You can pass variables of different data types into the string. The example below passes an integer and a string data type:

package main
import (
    "fmt"
)
func main() {
    fmt.Printf("%d:%s", 2016, "year")
}

2016:year
Program exited.

Video

Video tutorial below

Exercises

1. Create a program with multiple string variables
2. Create a program that holds your name in a string.

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