汇编:用于读取用户输入的文件描述符0或2 [英] Assembly: file descriptor 0 or 2 for reading user input

问题描述

我正在学习汇编，并且有不同的文件描述符用于读取用户输入.

I am learning assembly and there were different file descriptors used for reading user input.

对于阅读键盘输入，我期望文件描述符为0(stdin)，但遇到了文章，其中使用了文件描述符2(stderr).

For reading keyboard entry, I was expecting file descriptor 0 (stdin), but came across this article where file descriptor 2 (stderr) was used.

;Read and store the user input
mov eax, 3
mov ebx, 2
mov ecx, num  
mov edx, 5          ;5 bytes (numeric, 1 for sign) of that information
int 80h

但是，我通常看到ebx改为设置为0:

However, I've commonly seen ebx set as 0 instead:

;Read and store the user input
mov eax, 3
mov ebx, 0
mov ecx, num  
mov edx, 5          ;5 bytes (numeric, 1 for sign) of that information
int 80h

我尝试将ebx设置为0和2，它们都可以正常工作而没有问题.您能告诉我哪个是更好的选择吗?还是我应该采用其他最佳实践方法?

I have tried setting ebx to 0 and 2, and they both work fine without issues. Can you explain to me which is the better option to use? Or is there other approaches I should take for best practices?

推荐答案

更好的选择是使用STDIN文件描述符(编号0).不过，您可以使用STDERR流(第2个)(实际上是输出流)进行读取:

The better option is to use the STDIN file descriptor (No. 0). Nevertheless, you can use the STDERR streaM (No. 2) - actually an output stream - for reading:

预计将打开stderr流以进行读写

如果重定向STDIN流，这是一个实际的解决方法.

This is a practical workaround, if the STDIN stream is redirected.

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