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

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.

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());
}