How to determine whether a specified character exists in Go language

Judgment method: 1. Use the index() function to judge. You can find the position where the specified character first appears in the string. The syntax is "strings.Index(str, specified character)". If it returns "- 1" does not exist, otherwise it exists. 2. Use the ContainsRune() function to determine whether the character is in another string. The syntax is "strings.ContainsRune(str, specified character)". If it exists, it returns true, otherwise it returns false.

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

During the development process, many times we need to determine whether a character is in another string. In the Go language, we can use the Index function to achieve this. If the Index function returns -1, it does not exist, otherwise it exists, it can also be implemented using Contains.

Method 1: Use the index() function to determine

Index() is used to find specified characters in a string. If it exists, return the position of the first occurrence. If it does not exist, return -1.

func Index(s, substr string) int

Parameters	Description
s	Original string.
substr	The string to retrieve.

Return value:

• Index() function returns a value of type int. If it is included, it returns the first occurrence of the The index of the string; otherwise, -1 is returned.

Example: Find a single character

Use the Strings.Index() function to count the first occurrence of a certain character in a string The output result of

package main
import (
	"fmt"
	"strings"
)
func main() {
	//使用 Strings.Index() 函数，统计字符串某个字符第一次出现的位置
	strHaiCoder := "I love Golang and I study Golang From HaiCoder"
	index := strings.Index(strHaiCoder, "l")
	fmt.Println("index =", index)
}

is not -1, which means the specified character exists.

Method 2: Use the ContainsRune() function to determine

Golang provides us with a more concise way to determine whether a character is in another character. A function in a string, the ContainsRune function.

func ContainsRune(s string, r rune) bool

Parameters	Description
s	Original string.
r	represents the characters to be retrieved.

Return value

• ContainsRune() function returns a bool type value. If it is contained, it returns true; otherwise, it returns false.

Example: Determine whether there is

package main
import (
	"fmt"
	"strings"
)
func main() {
	//使用 Strings.ContainsRune() 函数，判断一个字符是否在另一个字符串中
	strHaiCoder := "嗨客网(HaiCoder)"
	StrContainersRune := strings.ContainsRune(strHaiCoder, 'C')
	fmt.Println("StrContainersRune =", StrContainersRune)
}

[Related recommendations: Go video tutorial、Programming teaching】

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