The fmemopen() function gives you a stdio FILE * object that refers to a buffer in memory. Replacing the open of test.jpg with a single call to fmemopen solves half the problem

fmemopen() 函数提供了一个 stdio FILE * 对象，该对象表示内存中的一个缓冲区。

youdao

In most cases, if what you want can be done with a higher-level library (stdio instead of raw reads and writes, for instance), you should do that; it gives you more insulation from possible quirks.

在大部分情况中，如果您希望可以使用更高级的库(举例来说，使用stdio，而不是原始的读写操作)，就应该这样做；这可以帮您更好地回避这些问题。

youdao

Starting with IDS v10, ontape operations can now be directed to or from "standard in" or "standard out" (STDIO), thereby providing support for a wider range of options.

从IDS v10开始，ontape操作可以被定向到标准输入或标准输出设备(“standard in”或“standard out”，STDIO)，因此为很多选项提供了支持。

youdao

stdio h It pretty much means open this file, standard IO dot H and just paste its contents right here.

它的大致上的意思是打开这个文件,然后把它的内容粘贴在那里。

哈佛公开课 - 计算机科学课程节选

include stdio h Well, remember this line; include standard IO dot H.

好的，请记住这一行。

哈佛公开课 - 计算机科学课程节选

stdio I don't even need standard IO because I'm not printing anything.

我甚至不需要,因为我不需要打印任何东西。

哈佛公开课 - 计算机科学课程节选