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In C/C++, there is no special method for comparing NULL values. We can use if statements to check whether a variable is null or not.Here, we will attempt to open a file in read mode that does not exist on the system. In this case, the function will return a NULL pointer. We can check whether it is NULL or not using an if statement. C Example to Check Variable is NULL or Not In this example, we check whether the file is exist or not using NULL. #include int main() { //try to open ... Read More
In this article, we will discuss how to extract a list of all the values from a Python dictionary. Following are various ways to retrieve list of all the values from a Python dictionary - Using dict.values() & list() Functions Using [] and * Using List comprehension ... Read More
In this article, we will learn about the control flow statements in JShell in Java. JShell is a new interactive command-line tool introduced in Java 9. This tool can also be called REPL (Read-Eval-Print-Loop) because it takes input, evaluates it, and returns output to the user via the command line. JShell Control Flow Statements Control flow statements are used to control the execution path of the code and are a fundamental part of the Java programming language. We can execute multiple-line control flow statements using JShell in the same way as Java. It recognizes multiple-line statements are prompts with the ... Read More
In this article, we will learn about the differences between Optional.ifPresentOrElse() and Optional.or() methods in Java 9. Both Optional.ifPresentOrElse() and Optional.or() methods were introduced in Java 9 to improve its functionality. Optional Class Optional Class is a part of java.util package, and it was introduced in Java 8. It is a container object that may or may not contain a non-null value. It helps in writing code without using too many null checks. The following are some of the common methods of the Optional Class: empty(): This method returns an empty Optional instance. ... Read More
In this article, we will learn to handle an exception in JShell in Java 9. We will learn about the JShell, exceptions in Java, JShell exceptions, their handling, and Types of exceptions in JShell with examples. What is JShell? JShell is a new command-line interactive REPL (Read-Evaluate-Print-Loop) tool introduced in Java 9 to evaluate declarations, statements, and expressions written in Java. This tool also allows us to execute Java code snippets and get immediate results. C:\Users\User>jshell | Welcome to JShell -- Version 9.0.4 | For an introduction type: /help intro jshell> JShell provides a fast and friendly environment that ... Read More
In this article, we will learn about the purpose of using the Optional.ifPresentOrElse() method in Java 9. The Optional Class The Optional class was introduced in Java 8. Many Java developers face null pointer exceptions to avoid this, we need to put null checks we need to put if, to check if a method is null we can put it in the if statement; otherwise, we have to put it in the else statement. And to check this, we need to put this at multiple points to avoid this situation, We use the Optional class. It avoids the null pointer ... Read More
Since Java 9, we are able to add private methods and private static methods in an interface. The advantage of using private methods in an interface is to reduce code duplication among default and static methods. For instance, if two or more default methods need to share some code, a private method can be created for the same and called from each of the default methods. Different Types of Variables and Methods in an Interface In Java 9, the following variables/methods have been defined in an interface. Constant Variables Abstract Method ... Read More
In this article, we will show you how to get a list of all the keys from a Python dictionary. We can get the list of all the keys from a Python dictionary using the following methods - Using dict.keys() Method Using list() & dict.keys() Function Using List Comprehension ... Read More
In this article, we will show you how to get a value for the given key from a dictionary in Python. Below are the 4 different methods to accomplish this task - Using Dictionary Indexing Using dict.get() Method Using keys() Function Using items() Function Assume we have taken a dictionary containing key-value pairs. We will return the value for a given key from a given input dictionary. Using dictionary indexing In Python, we can retrieve the value from a dictionary by using dict[key]. Example 1 The following program returns the index of the value for a given key ... Read More
A tuple is an ordered and immutable collection of Python objects separated by commas. Like lists, tuples are sequences. Tuples differ from lists in that they can not be modified, whereas lists can, and they use parentheses instead of square brackets. Though we can not change individual elements of a tuple, the del operator works with them. In this article, we are going to discuss the use of the del operator on a tuple. The del Operator with Tuples The del operator in Python is used to delete variables from the current scope. When you use "del" on a tuple ... Read More