函数的作用是：输出格式化字符串到流（例如：文件或数据库）。

The vfprintf() function writes a formatted string to a specified output stream (example: file or database).

youdao

But if you avoid all of these minutia and focus really just on the idea, it looks like what was a blue say block, a so called statement, is now going to be something called printf where the F happens to stand for formatted.

但是如果你抛开所有这些繁琐的细节，把注意力集中到,它的编程思想，那么它只不过一个蓝色的say程序块，是一个声明,即所谓的printf函数，其中的f是,用于格式化输出。

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