在C升压过程库的输出++ [英] output with boost process library in c++

问题描述

我用升压过程，并使用主教程页面。

I use boost process and use a default code in main tutorials page.

我已经运行此code，并没有显示任何输出！

I have run this code and it didn't print any output!

#include <boost/process.hpp> 
#include <string> 
#include <vector> 
#include <iostream> 

namespace bp = ::boost::process; 

int main() 
{ 
    std::string exec = "bjam"; 

    std::vector<std::string> args; 
    args.push_back("--version"); 

    bp::context ctx; 
    ctx.stdout_behavior = bp::capture_stream(); 

    bp::child c = launch(exec, args, ctx);

    bp::pistream &is = c.get_stdout(); 
    std::string line; 
    while (std::getline(is, line)) 
    std::cout << line << std::endl; 
} 

任何一个可以帮我解决这个问题？

can any one help me with this problem?

这code出口<一个href=\"http://www.highscore.de/boost/process/process/tutorials.html#process.tutorials.read_from_child\"相对=nofollow>这里。

谢谢！

推荐答案

您可能没有检查该进程是否成功启动。我可以简单地使用 /斌/ LS 而不是具有良好的成功：

You probably didn't check whether the process is successfully launched. I can simply use /bin/ls instead with good success:

// 
// Boost.Process 
// ~~~~~~~~~~~~~ 
// 
// Copyright (c) 2006, 2007 Julio M. Merino Vidal 
// Copyright (c) 2008 Boris Schaeling 
// 
// Distributed under the Boost Software License, Version 1.0. (See accompanying 
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 
// 

#include <boost/process.hpp> 
#include <string> 
#include <vector> 
#include <iostream> 

namespace bp = ::boost::process; 

bp::child start_child() 
{ 
    std::string exec = "/bin/ls"; 

    std::vector<std::string> args; 
    args.push_back("-ltrah"); 

    bp::context ctx; 
    ctx.stdout_behavior = bp::capture_stream(); 

    return bp::launch(exec, args, ctx); 
} 

int main() 
{ 
    bp::child c = start_child(); 

    bp::pistream &is = c.get_stdout(); 
    std::string line; 
    while (std::getline(is, line)) 
        std::cout << line << std::endl; 
} 

请注意，使用LS失败 - 没有错误消息

Note that using "ls" fails - without an error message.

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