Question

I’ve been cracking heads on how to achieve this in C++:

string format = "what is your %s";  
new_string = sprintf(buffer, format, name);

Any help would be very much appreciated.

Thanks!

Answer 1

Use format.c_str():

string format = "what is your %s";  
int total = sprintf(buffer, format.c_str(), name);

Also note the returned value is not the new string, it is the buffer which is the output string. The returned value is actually the total number of characters written. This count does not include the additional null-character automatically appended at the end of the string. On failure, a negative number is returned (see doc here).

But in C++, std::ostringstream is better and typesafe, as @Joachim explained in his answer.