No matching function call for ostringstream `.str()`

Question

I have a function which is defined as

void writeSite(string& site, const string& contentType);

Now I am building my string with the std::ostringstream function.

After finishing the string I want to call the writeSite function. But I get the following error:

no matching function for call to ‘writeSite(std::basic_ostringstream<char>::__string_type, const char [17])’
   writeSite(body.str(), "application/json");

I can solve the problem if I first save the ostringstream to a new std::string variable and then call the writeSite function.

But I was wondering, if there is a better option?

  std::ostringstream body;

  body << "{";

  // some more string building

  body << "}";

  std::string sbody = body.str();

  writeSite(sbody, "application/json");

Sorry, but this is a prime example why a [mcve] is required. I'm halfway sure you could have found that little error yourself. — Ulrich Eckhardt, Mar 24 '18 at 12:06
Can you change the signature of the function to `void writeSite(const string& site, const string& contentType);`? — Phil Brubaker, Mar 24 '18 at 12:06

score 2 · Accepted Answer · answered Mar 24 '18 at 12:07

When you do

writeSite(body.str(), "application/json");

the string object returned by body.str() is temporary. And non-constant references can not bind to temporary objects.

A simple solution is to make the site argument const just like you have done for the contentType argument (which would otherwise suffer from the same problem).

No matching function call for ostringstream `.str()`

1 Answers1