How to Perform Case-Insensitive String Searches in Go?

Case Insensitive String Search in Go

When searching through files for specific strings, it can be necessary to perform case-insensitive searches to ensure all occurrences are captured. This is especially useful when working with text that may contain both uppercase and lowercase characters.

In Go, the strings.EqualFold() function provides a convenient solution for case-insensitive string matching. It compares two strings and returns true if they are equal, regardless of character case. This function even handles Unicode characters, making it suitable for a wide range of use cases.

For example, let's consider the following scenario: you need to search for the string "Update" in a file. You want the search to match both "Update" and "update", as they are considered equivalent in a case-insensitive context.

To accomplish this, you can use the strings.EqualFold() function as follows:

package main

import (
    "fmt"
    "strings"
)

func main() {
    if strings.EqualFold("Update", "update") {
        fmt.Println("Match found")
    }
}

In this example, the strings.EqualFold() function will return true, indicating that "Update" and "update" are considered equal when case is ignored.

For a more comprehensive example, consider the following program that showcases how to perform a case-insensitive search within a file:

package main

import (
    "bufio"
    "fmt"
    "os"
    "strings"
)

func main() {
    // Open the file for reading
    file, err := os.Open("file.txt")
    if err != nil {
        panic(err)
    }
    defer file.Close()

    // Create a scanner to iterate over the file line by line
    scanner := bufio.NewScanner(file)

    // Specify the target string to search for
    target := "Update"

    // Read the file line by line
    for scanner.Scan() {
        line := scanner.Text()

        // Perform a case-insensitive search for the target string
        if strings.Contains(strings.ToLower(line), strings.ToLower(target)) {
            fmt.Println("Match found in line:", line)
        }
    }
}

In this program, the strings.Contains() function is used to search for the lowercase version of the target string within the lowercase version of each line in the file. This ensures that both "Update" and "update" are matched.

The output of the program will be a list of lines that contain the target string, regardless of its case. This demonstrates how to perform case-insensitive string searches in Go using the strings.EqualFold() and strings.Contains() functions.

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