如何修复：C++ 中的双重释放或损坏（出）中止（核心转储）

Question

我最近一直在处理我的 C++ 项目，我运行遇到了可执行文件的问题：

    std::string commanddata;
    std::string input;
    std::string cmdname;
    int commandlength = 0;
    if (commandlength == 0){}else{} // This is so that G++ doesn't complain that I have got a variable and never used it (I'm compiling at -Werror)
    while (true)
    {        
        input = DS_IO.kscanf(">>>"); // This is a specific function to get input from the user
        // Record the command length
        int commandlength = sizeof(input);

        // Make sure that the user doesn't just send us nothing
        if (commandlength <= 0)
            {
                continue;
            }
            else
            {
                // Get the first word from the command
            std::stringstream sstream(input);
            sstream >> cmdname;
            // Loops through the input string to remove everything up to and including a space delimiter
            for (int i = 0; i <= commandlength; i++)
            {
                if (input[i] == 32)
                {
                    commanddata = input;
                    commanddata.erase(input.begin(), input.begin() + i);
                    break;
                }
                else
                {
                    continue;
                }
            }
            // print out the data to make sure it's all working
            std::cout << "What you entered: " << input << std::endl;
            std::cout << "The command name: " << cmdname << std::endl;
            std::cout << "The command metadata: " << commanddata << std::endl;
        }
    }

代码工作正常，但我的问题是一旦到达循环末尾，它就会崩溃并给出此错误：

预期行为：

chemeriov@mikumputer:~/dev/DigitalSledgehammer$ ./a.out
>>>echo Hello world
What you entered: Hello world
The command name: echo
The command metadata: Hello world
>>>

经验行为：

chemeriov@mikumputer:~/dev/DigitalSledgehammer$ ./a.out
>>>echo Hello world
What you entered:  Hello world
The command name: echo
The command metadata:  Hello world

double free or corruption (out)
Aborted (core dumped)
chemeriov@mikumputer:~/dev/DigitalSledgehammer$

如何解决这个问题？

Answer 1

sizeof(input)是一个常量，比如16字节。要查找字符串的长度，请调用 input.length() 方法。

Answer 2

非常感谢@Soonts，他解决了我的问题！

另一个问题，commanddata.erase( input.begin()显然是错误的，一个容器不能擦除其他不相关容器内的范围。正确的用法是 something.erase(something.begin(), ..

你可以清楚地看出我是个菜鸟:)

如何修复：C++ 中的双重释放或损坏（出）中止（核心转储）

How to fix: double free or corruption (out) Aborted (core dumped) in C++

c++

gcc

command-line

g++