c++ - how to reuse stringstream

Question

These threads do NOT answer me:

resetting a stringstream

How do you clear a stringstream variable?

std::ifstream file( szFIleName_p );
if( !file ) return false;

// create a string stream for parsing

std::stringstream szBuffer;

std::string szLine;     // current line
std::string szKeyWord;  // first word on the line identifying what data it contains

while( !file.eof()){

    // read line by line

    std::getline(file, szLine);

    // ignore empty lines

    if(szLine == "") continue;

    szBuffer.str("");
    szBuffer.str(szLine);
    szBuffer>>szKeyWord;

szKeyword will always contain the first word, szBuffer is not being reset. I can't find a clear example anywhere on how to use stringstream.

New code after answer:

...
szBuffer.str(szLine);
szBuffer.clear();
szBuffer>>szKeyWord;
...

Ok, thats my final version:

std::string szLine;     // current line
std::string szKeyWord;  // first word on the line identifying what data it contains

// read line by line

while( std::getline(file, szLine) ){

    // ignore empty lines

    if(szLine == "") continue;

    // create a string stream for parsing

    std::istringstream szBuffer(szLine);
    szBuffer>>szKeyWord;

Answer 1

You didn't clear() the stream after calling str(""). Take another look at this answer, it also explains why you should reset using str(std::string()). And in your case, you could also reset the contents using only str(szLine).

If you don't call clear(), the flags of the stream (like eof) wont be reset, resulting in surprising behaviour ;)