How to Redirect stdout/stderr to a String in C ?

Redirecting stdout/stderr to a String in C

While there are numerous discussions on redirecting stdout/stderr to files, it is also possible to redirect these outputs to a string. This article explores how to accomplish this with the help of std::stringstream and a guard class.

Answer:

To redirect stdout/stderr to a string, you can employ std::stringstream. Here's how it works:

<code class="cpp">std::stringstream buffer;
std::streambuf * old = std::cout.rdbuf(buffer.rdbuf());

std::cout << "Bla" << std::endl;

std::string text = buffer.str(); // text now contains "Bla\n"</code>

This method captures the console output into a string.

To ensure proper cleanup, you can utilize a guard class:

<code class="cpp">struct cout_redirect {
    cout_redirect( std::streambuf * new_buffer ) 
        : old( std::cout.rdbuf( new_buffer ) )
    { }

    ~cout_redirect( ) {
        std::cout.rdbuf( old );
    }

private:
    std::streambuf * old;
};</code>

By using this guard, you can rest assured that the buffer is always reset, ensuring proper console I/O handling.

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