How do I check if a StringStream variable is empty/null?

Question

Just a quick question here guys. I've been searching to no avail so far.

A bit more info here:

stringstream report_string;  report_string << "some string here..."; 

In my code itself are various conditions for assigning values to the report_string variable.

I'd like to check whether it was assigned a value or not.

Answer 1

myStream.rdbuf()->in_avail() can be used to get the count of available characters ready to be read in from a stringstream, you can use that to check if your stringstream is "empty." I'm assuming you're not actually trying to check for the value null.

For example if you want to extract an int from a stringstream and then see if there were any left over characters (ie. non-numeric) you could check if myStream.rdbuf()->in_avail() == 0.

Is that something similar to what you're trying to do? I'm not sure if there's better ways but I've done this in the past and it's worked fine for me.

https://en.cppreference.com/w/cpp/io/basic_streambuf/in_avail

EDIT: I see you just updated your question as I posted.

Answer 2

An easy check would be to see if the string content of the stream is empty or not:

#include<assert.h> #include<sstream>  int main(){ std::stringstream report_string; report_string << ""; // an empty strin g  //emptiness check of stringstream assert(report_string.str().empty()); }