You also have to look at the kinds of problems that are being solved with the language. When is the last time you wrote a program in PHP that actually required comments? The vast majority of PHP is used for a specific type of application that doesn't require comments to understand. C/C++ on the other hand, is often used where finer control of the hardware is required, and anybody who has had to interact with hardware through code knows that it can be miserable experience sometimes.
It also helps to looks at the experience of the programmers who tend to use a particular programming language. All programmers start out thinking they are hot shots. After five or more years of experience they turn into real hot shots, and actually comment their code.
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You also have to look at the kinds of problems that are being solved with the language. When is the last time you wrote a program in PHP that actually required comments? The vast majority of PHP is used for a specific type of application that doesn't require comments to understand. C/C++ on the other hand, is often used where finer control of the hardware is required, and anybody who has had to interact with hardware through code knows that it can be miserable experience sometimes. It also helps to looks at the experience of the programmers who tend to use a particular programming language. All programmers start out thinking they are hot shots. After five or more years of experience they turn into real hot shots, and actually comment their code.