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How to remove all non-alphanumeric characters from a string in Kotlin

How to remove all non-alphanumeric characters from a string in Kotlin.

Here's a detailed step-by-step tutorial on how to remove all non-alphanumeric characters from a string in Kotlin:

Step 1: Create a Kotlin function​

Start by creating a Kotlin function that takes a string as input and returns a new string with non-alphanumeric characters removed. You can name the function removeNonAlphanumericChars or any other name you prefer.

Step 2: Initialize an empty string​

Inside the function, initialize an empty string that will store the result.

Step 3: Iterate over each character in the input string​

Use a for loop to iterate over each character in the input string. You can access each character using the indexing operator [].

Step 4: Check if the character is alphanumeric​

Inside the loop, check if the current character is alphanumeric using the isLetterOrDigit() function. This function returns true if the character is a letter or a digit, and false otherwise.

Step 5: Append alphanumeric characters to the result string​

If the current character is alphanumeric, append it to the result string using the plus operator (+).

Step 6: Return the result string​

After the loop finishes, return the result string.

Here's an example implementation of the removeNonAlphanumericChars function:

fun removeNonAlphanumericChars(input: String): String {
    var result = ""

    for (char in input) {
        if (char.isLetterOrDigit()) {
            result += char
        }
    }

    return result
}

You can now use the removeNonAlphanumericChars function to remove non-alphanumeric characters from a string. Here's an example usage:

val input = "Hello, World! 123"
val output = removeNonAlphanumericChars(input)
println(output) // Output: HelloWorld123

This will remove all non-alphanumeric characters from the input string and print the result.

Alternatively, you can also use regular expressions to remove non-alphanumeric characters from a string. Kotlin provides the replaceAll() function, which allows you to replace all occurrences of a pattern in a string. Here's an example using regular expressions:

fun removeNonAlphanumericChars(input: String): String {
    return input.replace("[^a-zA-Z0-9]".toRegex(), "")
}

In this example, the regular expression pattern "a-zA-Z0-9" matches any character that is not a letter or a digit. The replaceAll() function replaces all occurrences of this pattern with an empty string, effectively removing all non-alphanumeric characters.

You can use the removeNonAlphanumericChars function in the same way as before to remove non-alphanumeric characters from a string.

That's it! You now know how to remove all non-alphanumeric characters from a string in Kotlin.