Golang String Contains

It is nearly impossible to build a practical program without using strings. The go programming language knows this and provides you with the string package. This package contains a collection of methods that allow you to perform a plethora of operations on string types.

One popular operation is to check if a string contains a substring. Go allows you to check if a specific set of characters is available in a string using the contains method.

This article will discuss how to use the contains method and look at a few examples of searching for a substring.

Strings.Contains()

The Go contains method is part of the strings package. Hence, you must import the “strings” package before using it.

The function takes a string and a substring as the parameters. It then checks if the string contains the specified substring. It returns a Boolean true if the substring is found and false if otherwise.

The syntax of the contains() method is as shown:

func Contains(str, substr string) bool

The “str” is the main string in which to search, and the “substr” refers to the substring to search for.

Practical Examples

Let us look at a few examples of using the contains() method.

Example 1

Consider the example below:

package main
import (
"fmt"
"strings"
)

func main() {
str := "LinuxHint - Home of the best tech articles."
substr := "tech"
fmt.Println(strings.Contains(str, substr))
fmt.Println(strings.Contains(str, "articles"))
fmt.Println(strings.Contains(str, "😊"))
fmt.Println(strings.Contains(str, "not there"))
}

In the above example, we check if the substring “tech” is contained in the str. In the first example, we use a variable name.

In the second example, we pass a string literal. This shows that you can pass either a string variable or a string literal.

In the third example, we check for a Unicode character as shown by the emoji. Since the character is not in the string, the function returns false, as shown in the output below:

:: output
true
true
false
false

Example 2

You can use conditional logic to perform an action if the substring is found in the string. Consider the example below:

package main
import (
"fmt"
"strings"
)
func main() {
str := "LinuxHint - Home of the best tech articles."
substr := "tech"
if strings.Contains(str, substr) {
fmt.Printf("substring found!")
} else {
fmt.Println("substring not found!")
}
}

The example uses the string.contains() method as the condition. This is because the function returns a Boolean value.

If the function finds the substring, the code inside the if block is executed; otherwise, the code inside the else block is run.

The resulting output is as:

$ go run contains.go
substring found!

Conclusion

Using this guide, you discovered how to search if a string contains a specific substring. The contains() method is very useful and makes your work easier. Consider using it.

Happy Coding!