CODEWITHSUNDEEP
c++c
Coder
Coder

Reputation: 3715

Integration of C++ in C infrastructure

C++ is real handy in most projects, but sometimes you just have to integrate with existing C style functions.

How do you do that in a neat way, especially, if you work with strings?

I had an idea that I could use construct like this:

std::string buffer;
buffer.resize(1024);

GetBackCStyleString(&buffer[0], 1024);

But this causes problems with string length, as it returns the resized length. Is there a better way to integrate C functions in C++ code?

Upvotes: 3

Views: 157

Answers (3)

Ben Voigt
Ben Voigt

Reputation: 283694

That's a good solution. If you want the size to be accurate, call resize again after the function returns and you can calculate the actual length.

e.g.

buffer.resize(GetBackCStyleString(&buffer[0], buffer.size());

if the function returns the length, or

GetBackCStyleString(&buffer[0], buffer.size()
buffer.resize(strlen(&buffer[0]));

otherwise.

Upvotes: 1

ThiefMaster
ThiefMaster

Reputation: 318518

Create a plain char somebuf[somesize]; buffer and let the C function write into that. Then create a std::string from it using std::string buffer(somebuf).

If the function just wants a const char * (i.e. an "input" parameter), simply pass yourStdString.c_str() to it.

Upvotes: 0

Armen Tsirunyan
Armen Tsirunyan

Reputation: 133024

buffer.c_str() if function takes const char* or const_cast<char*>(buffer.c_str()) if function takes char*. In the latter case be cautious

Upvotes: 0

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