鏡像控制檯輸出到C++文件

#ifndef MYSTREAMBUF_H 
#define MYSTREAMBUF_H 

template <typename charT, typename traits = std::char_traits<charT> > 
class mystreambuf : public std::basic_streambuf<charT, traits> 
{ 
public: 
    // The size of the input and output buffers. 
    static const size_t BUFF_SIZE = 1024; 
    typedef traits traits_type; 
    typedef typename traits_type::int_type int_type; 
    typedef typename traits_type::pos_type pos_type; 
    typedef typename traits_type::off_type off_type; 

    // You can use any method that you want, but here, we'll just take in a raw streambuf as a 
    // slave I/O object. xor_char is what each character is xored with before output. 
    explicit mystreambuf(std::streambuf* buf) 
     : out_buf_(new charT[BUFF_SIZE]) 
    { 
     // ADDED: store the original cout stream and open our output file 
     this->original_cout = buf; 
     outfile.open("test.txt"); 

     // Initialize the put pointer. Overflow won't get called until this buffer is filled up, 
     // so we need to use valid pointers. 
     this->setp(out_buf_, out_buf_ + BUFF_SIZE - 1); 
    } 

    // It's a good idea to release any resources when done using them. 
    ~mystreambuf() { 
     delete [] out_buf_; 
     // ADDED: restore cout, close file 
     std::cout.rdbuf(original_cout); 
     outfile.flush(); 
     outfile.close(); 
    } 

protected: 
    // This is called when there are too many characters in the buffer (thus, a write needs to be performed). 
    virtual int_type overflow(int_type c); 
    // This is called when the buffer needs to be flushed. 
    virtual int_type sync(); 


private: 
    // Output buffer 
    charT* out_buf_; 
    // ADDED: tracking the original std::cout stream & the file stream to open 
    std::streambuf* original_cout; 
    std::ofstream outfile; 
}; 

#endif

mystreambuf.cpp

// Based on class by perfectly.insane from http://www.dreamincode.net/code/snippet2499.htm 

#include <fstream> 
#include <iostream> 
#include <streambuf> 

#include "mystreambuf.h" 

// This function is called when the output buffer is filled. 
// In this function, the buffer should be written to wherever it should 
// be written to (in this case, the streambuf object that this is controlling). 
template <typename charT, typename traits> 
typename mystreambuf<charT, traits>::int_type 
mystreambuf<charT, traits>::overflow(typename mystreambuf<charT, traits>::int_type c) 
{ 
    charT* ibegin = this->out_buf_; 
    charT* iend = this->pptr(); 

    // Reset the put pointers to indicate that the buffer is free 
    // (at least it will be at the end of this function). 
    setp(out_buf_, out_buf_ + BUFF_SIZE + 1); 

    // If this is the end, add an eof character to the buffer. 
    // This is why the pointers passed to setp are off by 1 
    // (to reserve room for this). 
    if(!traits_type::eq_int_type(c, traits_type::eof())) { 
     *iend++ = traits_type::to_char_type(c); 
    } 

    // Compute the write length. 
    int_type ilen = iend - ibegin; 

    // ADDED: restore cout to its original stream, output to it, output to the file, then set cout's stream back to this, our streambuf) 
    std::cout.rdbuf(original_cout); 
    out_buf_[ilen] = '\0'; 
    std::cout << out_buf_; 
    outfile << out_buf_; 
    std::cout.rdbuf(this); 

    return traits_type::not_eof(c); 
} 

// This is called to flush the buffer. 
// This is called when we're done with the file stream (or when .flush() is called). 
template <typename charT, typename traits> 
typename mystreambuf<charT, traits>::int_type 
mystreambuf<charT, traits>::sync() 
{ 
    return traits_type::eq_int_type(this->overflow(traits_type::eof()), 
            traits_type::eof()) ? -1 : 0; 
} 


int main(int argc, char* argv[]) { 
    mystreambuf<char> filter(std::cout.rdbuf()); 
    std::cout.rdbuf(&filter); 
    std::cout << "Hello World" << std::endl; 

    return 0; 
}

希望這有助於。乾杯

來源

2012-03-19 17:06:58 octal9

鏡像控制檯輸出到C++文件

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