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**D**, also known as **D**, is a general-purpose programming language with static typing, designed by Walter Bright. It was first released in 1999 and is currently developed by Digital Mars. **D** is a descendant of the C++ programming language, but it has a number of features that make it more modern and efficient. These include a garbage collector, a type system that supports generics, and a module system that makes it easy to organize code. **D** is used for a variety of applications, including systems programming, embedded systems, and graphics. **Sources:** * [D Programming Language](https://dlang.org/) * [D Programming Language Wikipedia Page](https://en.wikipedia.org/wiki/D_(programming_language))

Ask the right questions secure the right D talent among an increasingly shrinking pool of talent.

First 20 minutes

General D app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in D application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you declare a variable in D?

You can declare a variable in D by specifying the type followed by the variable name. For example, 'int x;' declares an integer variable named x.

What are the basic data types in D?

The basic data types in D include int, float, double, bool, char, wchar, dchar, and void.

How would you define a function in D?

A function in D is defined by specifying the return type, followed by the function name, parentheses for parameters, and then the function body enclosed in curly braces. For example, 'int add(int x, int y) { return x + y; }' defines a function that adds two integers.

What is the use of 'auto' keyword in D?

The 'auto' keyword in D is used for type inference. It allows the compiler to automatically determine the type of the variable at compile time.

How would you create an array in D?

You can create an array in D by specifying the type followed by the variable name and square brackets. For example, 'int[] arr;' creates an integer array named arr.

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What you’re looking for early on

Does the candidate have a good understanding of the D programming language?

Have they demonstrated problem-solving skills during the interview?

Do they show a strong grasp of data structures and algorithms?

Has the candidate shown they can work well in a team?

Next 20 minutes

Specific D development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

What are associative arrays in D?

Associative arrays in D are a form of array that can be indexed not only with numbers, but also with any other type. They are similar to hash tables in other languages.

Describe the difference between static and dynamic arrays in D.

Static arrays in D have a fixed size that is known at compile time, while dynamic arrays can change their size at runtime. Static arrays are allocated on the stack, while dynamic arrays are allocated on the heap.

How would you handle exceptions in D?

Exceptions in D are handled using try-catch blocks. The 'try' block contains the code that might throw an exception, and the 'catch' block contains the code to execute if an exception is thrown.

What is the purpose of 'immutable' keyword in D?

The 'immutable' keyword in D is used to declare that a variable's value cannot be changed after it is initialized. This is useful for creating constants and for thread safety.

How would you create a class in D?

A class in D is created using the 'class' keyword followed by the class name and the class body enclosed in curly braces. For example, 'class MyClass { }' creates a class named MyClass.

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At this point, a skilled D engineer should demonstrate strong problem-solving abilities, proficiency in D programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with D.

What does this simple D code do?
import std.stdio;

void main() {
    writeln('Hello, World!');
}
This code prints 'Hello, World!' to the standard output.
What will be the output of this D code?
import std.stdio;

void main() {
    int a = 5;
    int b = 10;
    writeln(a + b);
}
This code will output '15' to the standard output.
What does this D code do?
import std.stdio, std.array;

void main() {
    int[] arr = [1, 2, 3, 4, 5];
    arr = arr.reverse.array;
    writeln(arr);
}
This code reverses the order of the elements in the array 'arr' and then prints the reversed array.
What does this D code do?
import std.stdio, std.concurrency;

void main() {
    spawn(&printer, 'Hello, World!');
}

void printer(string text) {
    writeln(text);
}
This code creates a new thread and runs the 'printer' function in that thread, passing 'Hello, World!' as an argument to the function.

Wrap-up questions

Final candidate for D Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle D application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are templates in D?

Templates in D are a way to write generic code that can work with different data types. They are similar to templates in C++ and generics in Java.

Describe the difference between structs and classes in D.

The main difference between structs and classes in D is that structs are value types and classes are reference types. This means that when a struct is assigned to a new variable or passed to a function, a copy of the value is made. But when a class is assigned to a new variable or passed to a function, a reference to the original object is used.

How would you implement inheritance in D?

Inheritance in D is implemented using the ':' operator. For example, 'class Child : Parent { }' creates a class named Child that inherits from the Parent class.

D application related

Product Perfect's D development capabilities

Beyond hiring for your D engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in D projects, and can engage in multiple capacities.

D Consultive assessments

D Application Conversion Assessment D Application Integration Assessment D Data & Database Integration Assessment

Custom D development projects

Custom D App Conversion D Custom App Development Process App UI Design for D Facelifts

Hiring guide for D Engineers

D Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the D engineer at this point.

D Consultive assessments

Custom D development projects