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How to pad a string with leading zeros in Kotlin

How to pad a string with leading zeros in Kotlin.

Here's a step-by-step tutorial on how to pad a string with leading zeros in Kotlin:

Step 1: Create a function to pad the string​

Start by creating a function that will take a string and the desired length of the padded string as parameters. This function will return the padded string.

fun padStringWithZeros(input: String, length: Int): String {
    // TODO: Implement padding logic here
}

Step 2: Check if padding is necessary​

Inside the padStringWithZeros function, start by checking if the length of the input string is already greater than or equal to the desired length. If it is, there's no need to pad the string, so simply return the input string as is.

if (input.length >= length) {
    return input
}

Step 3: Pad the string with zeros​

If the length of the input string is less than the desired length, you will need to pad the string with leading zeros. Kotlin provides a handy String.padStart extension function for this purpose. Use it to pad the string with zeros until it reaches the desired length.

val paddedString = input.padStart(length, '0')
return paddedString

Step 4: Test the function​

To ensure that the function works correctly, it's a good idea to test it with different inputs. Here are a few examples:

println(padStringWithZeros("123", 5)) // Output: "00123"
println(padStringWithZeros("42", 4)) // Output: "0042"
println(padStringWithZeros("987654321", 9)) // Output: "987654321"

Step 5: Use the function in your code​

Now that you have a working function to pad strings with leading zeros, you can use it wherever you need to format strings in this way. Simply call the padStringWithZeros function and pass in the appropriate parameters.

val input = "42"
val length = 6
val paddedString = padStringWithZeros(input, length)
println(paddedString) // Output: "000042"

That's it! You've successfully learned how to pad a string with leading zeros in Kotlin. You can now use this knowledge to format strings as needed in your Kotlin projects.