Question

Originally asked here.

If I send “Hello world” to cin with the following code…

string str,msg;
getline(cin,str);
stringstream ss(str);
char c;
while(ss >> noskipws >> c)
    msg += c;

…results in msg = "Hello World".

But if I use string c instead of char c, msg is empty.

I am compiling with:
gcc (Ubuntu 4.4.3-4ubuntu5) 4.4.3

Why do I get an empty string?

Answer 1

Here’s an interesting quote from cplusplus.com:

Notice that many extraction operations consider the whitespaces themselves as the terminating character, therfore, with the skipws flag disabled, some extraction operations may extract no characters at all from the stream.

Remove the noskipws if you want to extract tokens into a string.

Generally, you should consider carefully, and then stick to one of, { line-based, token-based, or character-based } extraction.