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Programming Articles
Page 1906 of 2547
Haskell Program to Call One Constructor from Another
In Haskell, we will call one constructor from another by using user-defined function. In the first example, we are going to use (newPerson name = Person name 10) constructor and in the second example, we are going to use (newPerson n a = Person { name = n, age = a }) constructor. In the third example, we are going to use (clonePerson p = p { name = name p ++ " clone" }) constructor and in the fourth example, we are going to use (clonePerson p = p { name = name p ++ " clone" }) ...
Read MoreHaskell Program to get total Bits Required for the Given Number using Library Function
Haskell has internal function like finiteBitSize, ceiling, logBase, length and showIntAtBase that can be used to get total bits required from the given number. In the first example, we are going to use (bits = finiteBitSize (fromIntegral x :: Int)) function and in the second example, we are going to use (bitsRequired n = ceiling (logBase 2 (fromIntegral (abs n) + 1))) function. In the third example, we are going to use (bitsRequired n = length $ showIntAtBase 2 intToDigit (abs n) "") function. Algorithm Step 1 − Import the internal libraries Step 2 − The bitsRequired function ...
Read MoreHaskell Program to Calculate the Logarithm Gamma of the Given Number
In Haskell, we will calculate the logarithm gamma of the given number by using Stirling’s approximation and Lanczos appromixation formula. In the first example, we are going to use Stirling’s approximation with (s = foldr (\(c, q) acc -> c + (q / (x + acc))) 0 (zip (tail p) q) in (log s) - t + log (sqrt (2 * pi) / x) + (c * log (1 + c / 12.0 - (c * c) / 360.0)) function and in the second example, we are going to use Lanczos approximation formula along with (lanczos = log $ ...
Read MoreHaskell Program to Round a Number to n Decimal Places
In Haskell, we can use round, printf and truncate functions to round a number to n decimal places. In the first example, we are going to use (roundTo n x = (fromInteger $ round $ x * (10^n)) / (10.0^^n)) function and in the second example, we are going to use (roundTo n x = read $ printf ("%." ++ show n ++ "f") x) function.In the third example, we are going to use (roundTo n x = fromIntegral (truncate $ x * 10^n) / 10^n). Algorithm Step 1 − The roundTo function is defined using round function Step ...
Read MoreHow to dismiss ViewController in Swift?
In Swift, we have a dismiss method of the class UIViewController that can be used to dismiss a ViewController in Swift. In this method, a Boolean value is used as an argument. There is an argument in this argument that asks whether the dismissed controller should be animated. By default, this is true in this method. The following example shows how to dismiss a UIViewController screen in Swift. First view controller setup In this step, we will set up the first view controller to present the second view controller. We will add a button to the first view controller, which ...
Read MoreHow to Apply Gradient to the background view of the iOS Swift App?
In iOS, there is a class CAGradientLayer to apply gradient colors to views. In this article, we will look at how you can use the CAGradientLayer class to apply gradients to the background of a view in iOS. The CAGradientLayer class provides different properties like colors, locations, points, frame, etc. We will use them to apply the gradient to a view. In last, we will use the insertSublayer method to add the gradient layer to the super view. To apply a gradient to the background view of an iOS Swift app, you can follow these steps − Step 1 - ...
Read MoreGet input value from TextField in iOS alert in Swift
Generally, we use UIAlertController to show an alert with a dismiss action button. But UIAlertController provides you with more flexibility to add UITextFields to the alert. Let's see some examples of different use cases. When you add a text field to the UIAlertController, you can take the input value entered in the text field. It is also possible to add multiple text fields. In this example, we will use the following steps to get input values from the text field in iOS. Basic Setup In this step, you will add a button object to the controller's view to present the ...
Read MoreMove the text field when the keyboard appears in Swift
In real iOS applications, most of the time you deal with UITextFields for taking various inputs. In order to make the text fields visible while editing, you can manage the constraints by updating them. To manage the constraints, you have to add observers for keyboard showing and hiding. In this article, we will move the text field when the keyboard appears with the following steps. Step 1 - Basic setup In this step, we will do some basic setup by adding a text field to enter the email address. We will add the text field at the bottom of the ...
Read MoreHow to stop unwanted UIButton animation on title change?
In iOS applications, you will often need to customize the button according to your requirements. When you add a button to the parent view, the button title is animated by default. But if you want to stop that default animation, you can use the custom button in UIKit. We will first create a situation where you can see this problem. Here is the basic setup. Initially, we will add a register button to the parent view with basic customization. We will add the constraints programmatically to the button to set the button's position. Step 1 − Create a button ...
Read MoreHow to set back button text in Swift?
By default, a view controller shows the text "Back" with an arrow on the back button in iOS. But you can set a custom title and icon for the back button item. Let's see an example of how to set custom back button text in Swift. In this example, we will set up two different view controllers to see the default behavior of the back button and how to set the custom back button text. First View Controller Setup In this step, we will set up the first view controller to push the second view controller. Here is the code ...
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