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Rules and recommendations included in this standard are designed to be operating system and platform independent. However, the best available solutions to these problems is are often platform specific. In most cases, we have attempted to provide appropriate compliant solutions for POSIX-compliant and Windows operating systems. In many cases, compliant solutions have also been provided for specific platforms such as Linux or OpenBSD. Occasionally, we also point out implementation-specific behaviors when these behaviors are of interest.
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Some vendors have extensions to C, and some also have implemented only part of the C standard before stopping development. Consequently, it is not possible to back up and only discuss C95, or C90. The vendor support equation is too complicated to draw a line and say that a certain compiler supports exactly a certain standard. Whatever demarcation point is selected, different vendors are be on opposite sides of it for different parts of the language. Supporting all possibilities would require testing the cross product of each compiler with each language feature. Consequently we have selected a demarcation point that is the most recent in time, so that the rules and recommendations defined by the standard will have be applicable for as long as possible.
The value of forward looking information increases with time for a while before it starts to decrease. The value of backward looking information starts to decrease immediately.
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