istringstream

[paolopiace]

I need to extract all the sequences of non-empty characters (i.e. words) from all lines in a ascii inp_file. The following code does not go beyond the very first non-empty string, i.e. item is repeatedly the very first word of the first line.

while (getline(inp_file, line)) {
while (istringstream(line) >> item) {
out_file << item << '\n';
}
}

I thought that istringstream applies the stream attributes to its argument, making it behaving like a stream.

What am I doing wrong? How can I extract all the words in inp_file?

[seymore15074]

You don't need the stringstream object to do that. Try:

while( inp_file >> item )
{
    //...
}

If you did want to get a string (line) at a time from the file and process it via a istringstream, it goes like this:

istringstream ss( line );  // create a stringstream from line
ss >> item;  // read a word from the stringstream 

Note that in the previous examples, inp_file was a previously declared ifstream and item was a previously declared string.

[paolopiace]

Seymore, Thanks a bunch! It works and I really appreciate it.

Now I must understand the synatx you used and also why mine was incorrect.

[seymore15074]

Visit the Reference section of this site. It has everything that you need to know about stream constructors and their operators.