C++ 清除cout缓冲区（c+；+；）

您好，我正在编写一个简短的程序来实现一个shell，我遇到了一个不寻常的问题。由于某些原因，我无法清除std:：cout缓冲区。该程序不会打印消息。我知道一个简单的解决方案是切换到std:：cerr，但是有没有办法让消息用cout打印？ 我尝试过的事情：

std:：cout.flush（）

将任何内容写入标准输出后插入

std:：endl

在输出流中插入

std:：flush

std:：cout.setf（std:：ios:：unitbuf）这是我发现的应该取消缓冲输出的东西

非常感谢您的帮助，以下是我的代码：

int main()
{
    //Tryed this to unbuffer cout, no luck.
    std::cout.setf(std::ios::unitbuf);

    std::string input;

    //Print out shell prompt and read in input from keyboard.
    std::cout << "myshell> ";   
    std::getline(std::cin, input);

    //**********************************************************************
    //Step 1) Read in string and parse into tokens.
    //**********************************************************************

    char * buf = new char[input.length() + 1];
    strcpy(buf, input.c_str());

    int index = 0;
    char * command[256]; 

    command[index] = std::strtok(buf, " ");    //Get first token.
    std::cout << command[index] << std::endl;

    while (command[index] != NULL)
    {
        ++index;
        command[index] = std::strtok(NULL," ");    //Get remaining tokens.
        std::cout << command[index] << std::endl;
    }   

    std::cout.flush(); //No luck here either

    //HERE IS WHERE MY PROBLEM IS.
    std::cout << index << " items were added to the command array" << std::endl;

    delete[] buf;

    return 0;   
}

intmain（）
{
//试着把这个解开，运气不好。
std:：cout.setf（std:：ios:：unitbuf）；
std：：字符串输入；
//打印外壳提示并从键盘读取输入。
std:：cout问题是，在
while
循环的最后一次迭代中，您正在将
NULL
发送到
cout
，这会导致UB，在您的情况下，会干扰
cout
。在将任何内容发送到
cout
之前，请检查
NULL
，您很好：

if (command[index] != NULL) {
    std::cout << command[index] << std::endl;
}

if（命令[索引]！=NULL）{
std:：cout如果您需要知道流发生了什么，请记住它们可以携带状态信息（）。以下代码可能有助于跟踪您的错误：

 try {
      std::cout.exceptions(std::cout.failbit);          
 } catch(const std::ios_base::failure& e) {
      std::cerr << "stream error: " << e.what() << std::endl;
      std::cout.clear();
 }

 // continue working with cout, because std::cout.clear() removed
 // failbit

这是您的代码的外观：

#include <cstring>
#include <string>
#include <iostream>
int main()
{
    //Tryed this to unbuffer cout, no luck.
    std::cout.setf(std::ios::unitbuf);

    std::string input;

    //Print out shell prompt and read in input from keyboard.
    std::cout << "myshell> ";   
    std::getline(std::cin, input);

    //**********************************************************************
    //Step 1) Read in string and parse into tokens.
    //**********************************************************************

    char * buf = new char[input.length() + 1];
    strcpy(buf, input.c_str());

    int index = 0;
    char * command[256]; 

    command[index] = std::strtok(buf, " ");    //Get first token.
    std::cout << command[index] << std::endl;

    while (command[index] != NULL)
    {
        ++index;
        command[index] = std::strtok(NULL," ");    //Get remaining tokens.
        std::cout << command[index] << std::endl;
    }

    // I added from here...
    if(not std::cout) {
      std::cerr << "cout is messed up... fixing it..." << std::endl;
      std::cout.clear();
    }
    // ... to here.

    std::cout.flush(); //No luck here either

    //HERE IS WHERE MY PROBLEM IS.
    std::cout << index << " items were added to the command array" << std::endl;

    delete[] buf;

    return 0;   
}

您似乎已经尝试了列出的所有内容。您确定发布的示例与实际代码匹配吗？什么环境（操作系统、编译器）顺便说一下，“代码”> CUT//CUT>是纯C++。我把C标记从你的帖子中删除了。我在Geany的Linux环境下编码。我将通过链接查看。我使用的编译器选项是：G++WALL-STD= C++ 0x-C“%F”构建选项：G++WALL-STD= C++ 0x-O“%E”“%F”在执行此操作时，我遇到了一个分段错误11
#include <cstring>
#include <string>
#include <iostream>
int main()
{
    //Tryed this to unbuffer cout, no luck.
    std::cout.setf(std::ios::unitbuf);

    std::string input;

    //Print out shell prompt and read in input from keyboard.
    std::cout << "myshell> ";   
    std::getline(std::cin, input);

    //**********************************************************************
    //Step 1) Read in string and parse into tokens.
    //**********************************************************************

    char * buf = new char[input.length() + 1];
    strcpy(buf, input.c_str());

    int index = 0;
    char * command[256]; 

    command[index] = std::strtok(buf, " ");    //Get first token.
    std::cout << command[index] << std::endl;

    while (command[index] != NULL)
    {
        ++index;
        command[index] = std::strtok(NULL," ");    //Get remaining tokens.
        std::cout << command[index] << std::endl;
    }

    // I added from here...
    if(not std::cout) {
      std::cerr << "cout is messed up... fixing it..." << std::endl;
      std::cout.clear();
    }
    // ... to here.

    std::cout.flush(); //No luck here either

    //HERE IS WHERE MY PROBLEM IS.
    std::cout << index << " items were added to the command array" << std::endl;

    delete[] buf;

    return 0;   
}

$ ./a.out
myshell> 1 2 3
1
2
3
cout is messed up... fixing it...
3 items were added to the command array