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Why do modern programming languages exclude goto? Explore the hidden history of this ancient grammar!
In computer science, control flow (or flow control) refers to the order in which individual statements, instructions, or function calls are executed or evaluated in an imperative program. This emphasis on explicit control flow is in sharp contrast to declarative programming languages. However, although the goto statement was common in early programming, modern programming languages are increasingly rejecting it. Why?
"The use of the GOTO statement is considered one of the most dangerous causes because it makes the control flow of the program confusing and difficult to trace."
Going back to the 1950s, the goto statement was widely used in early programs because of its simplicity and straightforwardness. With tags, programmers can make the execution order of code flexible by transferring control. However, as program complexity increases, this control method is gradually considered no longer ideal. Most experts point out that this unrestricted flow of control makes the code difficult to maintain.
Especially after the famous computer scientist Edsger Dijkstra published the landmark paper "Go To Statement Considered Harmful", the disadvantages of the goto language began to receive more widespread attention. Dijkstra clearly pointed out in the article that excessive use of goto will lead to confusion in program structure and difficult to understand control flow, and advocated the creation of more clear control structures, such as if-else, while loops, etc.
"Structured programming is a design style that emphasizes the use of clear control structures that make code easier to understand and maintain."
With the continuous evolution of programming concepts, many programming languages have gradually integrated the concept of structured programming and advocated the use of clear control structures to replace goto. For example, in languages such as C, Java, and Python, control structures such as if, while, and for are widely used, which greatly improves the readability and maintainability of programs.
The evolution of control flow
The evolution of control flow statements reflects changes in programming philosophy since the early days of computer science. From the initial goto statement to the later if-else conditional statements, while and for loops, these changes not only make the code more expressive, but also make the program logic clearer.
For example, the concept of "structured programming" in modern languages makes the flow of each piece of code more formal, helping developers quickly capture the intent of the program and implement more efficient error handling. This method not only effectively reduces the number of lines of code, but also improves the testability of the program.
"Dijkstra's theory proves that any program containing goto can be converted into a form without goto, using only selection (IF-THEN-ELSE) and loops (WHILE, etc.), which enhances the structure of programming."< /p>
The impact of structured programming
Structured programming has since become one of the core concepts of modern programming. It guides the design direction of countless programming languages to keep programs clean and clear. Many programming education courses regard structured programming as the foundation, pushing students to learn to write programs that are readable and easy to maintain.
However, some debate still exists among programmers. Some argue that stripping goto statements too far can lead to verbose programming in certain situations. This debate highlights the delicate balance between complexity and flexibility in control flow design. Do goto statements need to be avoided completely in all cases, or should they be used in moderation based on specific scenarios?
Conclusion
In short, although the goto statement was once a powerful tool, with the development of programming, it also exposed many potential problems. Modern programming has evolved toward more efficient and explicit control flow structures. So, should we unconditionally exclude goto in the design of modern programming languages, or leave a little room for flexibility for future development?
