Bjarne Stroustrup: C++ | Lex Fridman Podcast #48 | Summary and Q&A

November 7, 2019
Lex Fridman Podcast
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Bjarne Stroustrup: C++ | Lex Fridman Podcast #48


C++ is a powerful and popular programming language that focuses on fast, stable, and robust code. It underlies many critical systems we rely on, and its creator, Bjorn Stroustrup, discusses the language's history, design principles, and features.

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Questions & Answers

Q: What was the first program Bjorn Stroustrup ever wrote?

Stroustrup's first program was a shape calculator in Algo 60, which calculated the shape of super ellipses and created star patterns by connecting points on the perimeter. He wrote this program during his second year of university.

Q: Why did Stroustrup fall in love with C++ programming language?

Stroustrup was drawn to C++ because it allowed him to build his own types, giving him the flexibility and control he desired in his programming. He appreciated the ability to express his ideas more directly in code and found C++ to be a simpler and more fun language compared to others he had used.

Q: What was the first breakthrough in programming languages?

The first major breakthrough in programming languages was the introduction of Fortran, which allowed programmers to write code in terms that humans used, rather than the language of the specific machine. This breakthrough provided portability and easier programming for engineers and scientists.

Q: How did Simula influence the development of C++?

Simula, a programming language designed for simulation, introduced the concept of classes and influenced the idea of object-oriented programming. Stroustrup learned about object-oriented programming from Simula, and C++ adopted the concept of classes, which are the user-defined types in the language.


In this conversation with Bjorn Stroustrup, the creator of the C++ programming language, he discusses the origins of C++, the importance of abstraction and efficiency, and the evolution of the language. He emphasizes the need for simplicity and cleanliness in code, and how static analysis can help achieve this. He also discusses the tension between high-level abstraction and efficiency, and how C++ aims to balance both. Stroustrup also touches on the importance of multiple language implementations and the future of C++.

Questions & Answers

Q: What was the first program Bjorn Stroustrup ever written?

Bjorn Stroustrup's first program was written during his second year of university and was a shape calculator of super ellipses that created star patterns.

Q: What was the first programming language Bjorn Stroustrup fell in love with?

Bjorn Stroustrup fell in love with Algol 60, as it was a simple language that served the needs of Niklaus Wirth at the time. However, he also mentioned his interest in Simula, a language that taught him the importance of having a strict type system to organize code.

Q: Can Bjorn Stroustrup give a brief history of programming languages?

Bjorn Stroustrup mentions that the first major improvement in programming languages was Fortran, which allowed programmers to write code that was natural to humans rather than a specific machine. He also mentions the importance of Simula in introducing the concept of classes and inheritance, which laid the foundation for object-oriented programming. He acknowledges the significance of languages like Lisp and functional languages, but also highlights the importance of languages like C++ that focus on efficiency and reliability.

Q: How does Bjorn Stroustrup view languages like Lisp and JavaScript in relation to C++?

Bjorn Stroustrup acknowledges the importance and popularity of languages like Lisp and JavaScript, but he also mentions his personal preferences and the constraints of the domains he works in. He prefers languages like C++ that offer a strong type system and allow for high performance, reliability, and deployment on a variety of hardware and environments.

Q: How does Bjorn Stroustrup balance high-level abstraction and efficiency in C++?

Bjorn Stroustrup emphasizes the importance of abstraction in achieving efficiency in C++. He follows the zero overhead principle, where abstractions should not add any additional cost compared to writing the equivalent code at a lower level. By providing tools and abstractions that allow programmers to express their ideas directly, C++ enables optimizations and performance improvements that would be difficult to achieve in lower-level languages. Additionally, he mentions the importance of simplicity and cleanliness in code to ensure reliability and maintainability.

Q: How does Bjorn Stroustrup inspire or ensure the attainment of high-level simplification in C++ code?

Bjorn Stroustrup recommends using a set of rules, such as the C++ Core Guidelines, to guide programmers in using the language effectively. These rules help limit common mistakes and ensure cleaner code. He also encourages the use of static analysis tools to catch mistakes and enforce adherence to the guidelines. By simplifying code and expressing ideas directly, programmers can create code that is easier to understand, maintain, and test.

Q: How does Bjorn Stroustrup approach the design of new features in C++ and the different implementations of the language?

Bjorn Stroustrup believes that the design and implementation of new features in C++ require considerations in three areas: programming techniques, programming language features, and implementation techniques. He highlights the importance of craftsmanship and experience in achieving the ideal balance of high-level abstraction and efficiency. He also supports the existence of different language implementations, as it fosters competition, innovation, and avoids monopolies or stagnation.

Q: Does Bjorn Stroustrup foresee the creation of a new implementation of C++ written from scratch in the future?

Bjorn Stroustrup mentions that there have been attempts to write new implementations of C++, and some have been successful and absorbed into existing implementations. He believes that someone may try again in the future but acknowledges that creating a new implementation from scratch is a significant challenge due to the complexity and evolution of the language.

Q: What are the key features of C++? How has the language evolved over time?

The key feature of C++ is its focus on using hardware efficiently while managing complexity through abstraction. It provides a way to manipulate machines at a low level, similar to C, but also offers support for object-oriented programming and other techniques. Over time, the language has evolved to add features like lambdas, move semantics, and concepts. The goal has always been to balance high-level abstraction with efficiency, and to provide tools and guidelines to help programmers write clean and reliable code.

Q: How does Bjorn Stroustrup view the future of C++?

Bjorn Stroustrup believes that there is still room for improvement in C++ and that it will continue to evolve. He mentions the importance of finding better solutions to complex problems and achieving higher levels of reliability, performance, and security. He also emphasizes the need to consider not just the language and its features, but also the application areas and implementation techniques. He encourages learning from other languages and using static analysis tools to catch errors and write better code.


Bjorn Stroustrup's discussion provides insights into the origins, evolution, and design principles of the C++ programming language. He emphasizes the need for simplicity, cleanliness, and abstraction in code, and the importance of balancing high-level abstraction with efficiency. Stroustrup highlights the advantages of having multiple implementations of C++ and the role of static analysis in catching mistakes and improving code quality. He acknowledges the future potential for further improvements in C++ and the necessity of staying ahead in terms of reliability, performance, and security.

Summary & Key Takeaways

  • C++ is a programming language known for its focus on fast, stable, and robust code, making it suitable for critical systems and applications.

  • Bjorn Stroustrup, the creator of C++, shares his personal journey and experiences with the language, as well as its evolution through various standards updates.

  • Stroustrup highlights the importance of understanding multiple programming languages and the benefits of learning from different paradigms, such as functional programming.

  • He emphasizes the key ideas behind C++, including the flexibility of types, the power of abstraction, and the use of object-oriented and generic programming paradigms.

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