python sys.stdout 和 C++ iostreams::cout [英] python sys.stdout and C++ iostreams::cout

问题描述

我假设 sys.stdout 将引用与在同一进程中运行的 iostreams::cout 相同的物理流，但情况似乎并非如此.以下代码使用名为write"的 Python 包装器调用 C++ 函数，并写入 cout:

I was assuming that sys.stdout would be referencing the same physical stream as iostreams::cout running in the same process, but this doesn't seem to be the case. The following code, which makes a call to a C++ function with a python wrapper called "write", that writes to cout:

from cStringIO import StringIO 
import sys 
orig_stdout = sys.stdout 
sys.stdout = stringout = StringIO() 
write("cout") # wrapped C++ function that writes to cout 
print "-" * 40 
print "stdout" 
sys.stdout = orig_stdout 
print stringout.getvalue() 

立即向控制台写入cout"，然后是分隔符---..."，最后，作为stringout.getvalue() 的返回值，字符串stdout".我的目的是在 stringout 中也捕获从 C++ 写入 cout 的字符串.有谁知道发生了什么，如果是，我如何捕获在 python 字符串中写入 cout 的内容?

immediately writes "cout" to the console, then the separator "---...", and finally, as the return value of stringout.getvalue(), the string "stdout". My intention was to capture in stringout also the string written to cout from C++. Does anyone know what is going on, and if so, how I can capture what is written to cout in a python string?

提前致谢.

推荐答案

sys.stdout 是一个写入标准输出的 Python 对象.它实际上不是标准输出文件句柄；它包装那个文件句柄.改变 sys.stdout 在 Python-land 中指向的对象不会以任何方式影响 stdout 句柄或 std::cout 流C++ 中的对象.

sys.stdout is a Python object that writes to standard output. It is not actually the standard output file handle; it wraps that file handle. Altering the object that sys.stdout points to in Python-land does not in any way affect the stdout handle or the std::cout stream object in C++.

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