我可以在C＃中使用stringstream作为内存流，如`MemoryStream`吗？

Question

In C/C++, strings are NULL terminated.

Could I use stringstream as a memory stream like MemoryStream in C#?

Data of memory streams may have \\0 values in the middle of data, but C++ strings are NULL terminated.

Answer 1

When storing character sequences in a std::string you can have included null characters. Correspondingly, a std::stringstream can deal with embedded null characters as well. However, the various formatted operations on streams won't pass through the null characters. Also, when using a built-in string to assign values to a std::string the null characters will matter, ie, you'd need to use the various overloads taking the size of the character sequence as argument.

What exactly are you trying to achieve? There may be an easier approach than traveling in string streams. For example, if you want to read the stream interface to interact with a memory buffer, a custom stream buffer is really easy to write and setup:

struct membuf
    : std::streambuf 
{
        membuf(char* base, std::size_t size) {
        this->setp(base, base + size);
        this->setg(base, base, base + size);
    }
    std::size_t written() const { return this->pptr() - this->pbase(); }
    std::size_t read() const    { return this->gptr() - this->eback(); }
};

int main() {
    // obtain a buffer starting at base with size size
    membuf       sbuf(base, size);
    std::ostream out(&sbuf);
    out.write("1\08\09\0", 6); // write three digits and three null chars
}

Answer 2

In C/C++, strings are NULL terminated.

• Two completely different languages (that have some commonality in syntax). But C is about as close to C++ as Jave is to C# (in that they are different).

Each language has their own string features.

• C uses a sequence of bytes that by convention is terminated by a '\\0' byte.
  • Commonly referred to as a C-String.
  • There is nothing special about this area of memory it is just a sequence of bytes.
  • There is no enforcement of convention and no standard way to build.
  • It is a huge area of bugs in C programs.
• C++ uses a class (with methods) std::string.

Could I use stringstream as a memory stream like MemoryStream in C#?

Sure. The Memory stream is a stream that is backed by memory (rather than a file). This is exactly what std::stringstream is. There are some differences in the interface but these are minor and use of the documentation should easily resolve any confusion.

Data of memory streams may have \\0 values in the middle of data, but C++ strings are NULL terminated.

This is totally incorrect.

• C-String are '\\0' terminated.
• C++ std::string are not null terminated and can contain any character

Answer 3

C and C++ are two different languages, in C sequence of continues character means string, and you can treat it as a memory part which can set/get its values, using memcpy() , memset() , memcmp() .

In C++ strings means a class of information which used to get correct data as string. So you can't treat it as a sequence of memory location with char type.