使用CString的MFC TextOut失败

Question

I use MFC TextOut to put some text on screen as follows

std::string myIntToStr(int number)
{
    std::stringstream ss;//create a stringstream
    ss << number;//add number to the stream
    return ss.str();//return a string with the contents of the stream
}


void MViewClass::DrawFunction()
{
    CClientDC aDC(this);
    // .. Drawing Code
    aDC.TextOut(27, 50, ("my age is " + myIntToStr(23)).c_str());

}

But I get error saying " cannot convert argument 3 from 'const char *' to 'const CString &'".

The documentation for TextOut shows a CString overload. I would like to use CString with TextOut as it allows me to use my myIntToStr converter. Any suggestions?

Answer 1

The code uses std::string's c_str , which returns const char* , not CString`. Try

void MViewClass::DrawFunction()
{
    CClientDC aDC(this);
    CString s("my age is ");
    s += myIntToStr(23).c_str();
    // .. Drawing Code
    aDC.TextOut(27, 50, s);
}

or just use CString::Format

void MViewClass::DrawFunction()
{
    CClientDC aDC(this);
    CString s;
    s.Format("my age is %d", 23);
    // .. Drawing Code
    aDC.TextOut(27, 50, s);
}

Answer 2

I assume that you use function myIntToStr to convert an int to a string elsewhere in you code, and that you current problem is how to display a C++ string with TextOut.

You could simply create a CString in the stack initialized from the std::string that way :

void MViewClass::DrawFunction()
{
    CClientDC aDC(this);
    // .. Drawing Code
    CString age(("my age is " + myIntToStr(23)).c_str());
    aDC.TextOut(27, 50, age);

}

As it is created on the stack, it will automatically vanish at the end of the method and you have not worry about allocation and deallocation.