Golang bytes.Contains() function is “used to check whether the given byte subslice is within byte slice.”
Syntax
func Contains(b, subslice []byte) boolParameters
- b: The byte slice in which we want to check for the presence of the subslice.
- subslice: The byte slice we’re looking for in b.
Return value
It returns true if the subslice is found within b and false otherwise.
Example 1: How to Use bytes.Contains() function
package main
import (
"bytes"
"fmt"
)
func main() {
b := []byte("Hello, Golang!")
sub := []byte("Go")
if bytes.Contains(b, sub) {
fmt.Println("b contains sub")
} else {
fmt.Println("b does not contain sub")
}
}Output
b contains subExample 2: Checking the Presence of a Byte Sequence in a File Content
package main
import (
"bytes"
"fmt"
"log"
"os"
)
func main() {
fileContent, err := os.ReadFile("new.txt")
if err != nil {
log.Fatalf("Error reading the file: %v", err)
}
sub := []byte("special_sequence")
if bytes.Contains(fileContent, sub) {
fmt.Println("The file contains the special sequence.")
} else {
fmt.Println("The file does not contain the special sequence.")
}
}Output
The file does not contain the special sequence.Example 3: Checking for Byte Prefixes
Suppose you want to check if a byte slice starts with a specific prefix.
package main
import (
"bytes"
"fmt"
)
func hasPrefix(b, prefix []byte) bool {
return bytes.Contains(b[:len(prefix)], prefix)
}
func main() {
b := []byte("Golang is awesome!")
prefix := []byte("Go")
if hasPrefix(b, prefix) {
fmt.Println("The byte slice starts with the prefix.")
} else {
fmt.Println("The byte slice does not start with the prefix.")
}
}
Output
The byte slice starts with the prefix.In this example, we defined a helper function hasPrefix() that uses bytes.Contains() function to check if a byte slice starts with a given prefix. The main() function then uses this helper function to determine if the byte slice b starts with the prefix “Go”.
That’s it.
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Krunal Lathiya is a seasoned Computer Science expert with over eight years in the tech industry. He boasts deep knowledge in Data Science and Machine Learning. Versed in Python, JavaScript, PHP, R, and Golang. Skilled in frameworks like Angular and React and platforms such as Node.js. His expertise spans both front-end and back-end development. His proficiency in the Python language stands as a testament to his versatility and commitment to the craft.