如何在c++中读取标准istream缓冲区？

发布于 2024-12-27 02:03:49 字数 1013 浏览 1 评论 0原文

我有以下问题。我必须实现一个类，该类具有一个属性，该属性是一个 char 指针，旨在指向对象的“代码”，如下所示：

class foo{
     private:
         char* cod;
         ...
     public:
         foo();
         void getVal();
         ...
}

依此类推。 getVal() 是一种从标准 istream 中获取代码并填充所有信息（包括代码）的方法。问题是，标识对象的“代码”不能超过一定数量的字符。这必须在不使用 getVal() 方法的自定义缓冲区的情况下完成，因此我不能执行以下操作：

//suppose the maximum number of characters is 50
void foo::getVal()
{
     char buffer[100];
     cin >> buffer;
     if (strlen(buffer) > 50) //I'm not sure this would work considering how the stream
                               of characters would be copied to buffer and how strlen
                               works, but suppose this tells me how long the stream of 
                               characters was.
     {
        throw "Exception";
     }
     ...
}

这是禁止的。我也无法使用自定义的 istream，也无法使用 boost 库。

我以为我可以很容易地找到 istream 保存其信息的地方，但我找不到它。我发现的只是提及其他类型的流。

有人可以告诉我这是否可以完成或者流在哪里保存其缓冲信息？

谢谢

原文

I have the following problem. I have to implement a class that has an attribute that is a char pointer meant to point to the object's "code", as follows:

class foo{
     private:
         char* cod;
         ...
     public:
         foo();
         void getVal();
         ...
}

So on, so forth. getVal() is a method that takes the code from the standard istream and fills in all the information, including the code. The thing is, the "code" that identifies the object can't be longer than a certain number of characters. This has to be done without using customized buffers for the method getVal(), so I can't do the following:

//suppose the maximum number of characters is 50
void foo::getVal()
{
     char buffer[100];
     cin >> buffer;
     if (strlen(buffer) > 50) //I'm not sure this would work considering how the stream
                               of characters would be copied to buffer and how strlen
                               works, but suppose this tells me how long the stream of 
                               characters was.
     {
        throw "Exception";
     }
     ...
}

This is forbidden. I also can't use a customized istream, nor the boost library.

I thought I could find the place where istream keeps its information rather easily, but I can't find it. All I've found were mentions to other types of stream.

Can somebody tell me if this can be done or where the stream keeps its buffered information?

Thanks

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阿楠 2025-01-03 02:03:49

是的，使用 strlen 肯定会起作用..您可以

   int main()
   {

    char buffer[10];
    std::cout << "enter buffer:" ;
    std::cin >>buffer;
    if(strlen(buffer)>6)
    std::cout << "size > 6";
    getch();
   }

为大于 6 个字符的输入编写一个示例程序，它将显示大小 > 6

yes using strlen would work definitely ..you can write a sample program

   int main()
   {

    char buffer[10];
    std::cout << "enter buffer:" ;
    std::cin >>buffer;
    if(strlen(buffer)>6)
    std::cout << "size > 6";
    getch();
   }

for inputs greater than size 6 characters it will display size >6

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