At least in PHP. Unfortunately in my experience the PHP documentation is not frequently read by PHP developers or even PHP internals developers. It seems to exist mainly for PHP hatebloggers, for whom it's a gold mine.
This illustrates some problems with the PHP way of doing things. For some reason the PHP internals community prefers to have this function continue to spit out garbage when given invalid inputs instead of throwing an error, especially if spitting out garbage is what was done in the past. The answer is always, "Don't do that. RTFM." but most developers don't read the documentation for each and every function that they use, but rather rely on the name of and common sense until there's a error. If there's no error, the documentation never gets read.
This illustrates some problems with the PHP way of doing things. For some reason the PHP internals community prefers to have this function continue to spit out garbage when given invalid inputs instead of throwing an error, especially if spitting out garbage is what was done in the past. The answer is always, "Don't do that. RTFM." but most developers don't read the documentation for each and every function that they use, but rather rely on the name of and common sense until there's a error. If there's no error, the documentation never gets read.