G 在 gcount，tell 和 Seekg 中代表什么？

在 std::iostream的 gcount、 tellg和 seekg成员中，克代表什么？那 pcount、 tellp和 seekp中的 P呢？

为什么不叫它们 count、 tell和 seek？

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C++ offers two pointers while navigating the file: the get pointer and the put pointer. The first one is used for read operations, the second one for write operations.

seekg() is used to move the get pointer to a desired location with respect to a reference point.

tellg() is used to know where the get pointer is in a file.

seekp() is used to move the put pointer to a desired location with respect to a reference point.

tellp() is used to know where the put pointer is in a file.

^{Main source: Quora, answer by Gunjan B. Yadav on Dec 1, 2017.}

最佳答案

In streams supporting both read and write, you actually have two positions, one for read (i.e. "get" denoted by "g") and one for write (i.e. "put" denoted by a "p").

And that's why you have a seekp (inherited from basic_ostream), and a seekg (inherited from basic_istream).

Side note: The language C has - in contrast to C++ - only one such function fseek for both pointers; There it is necessary to re-position the pointer when switching from read to write and vice versa (cf., for example, this answer). To avoid this, C++ offers separate functions for read and write, respectively.