How to Effectively Reset a Stringstream?

Resetting Stringstreams Effectively

When attempting to clear a stringstream to reuse it for further input and extraction, it's essential to employ the appropriate techniques to fully reset the stream. Consider the following example:

stringstream parser;

parser << 5;
short top = 0;
parser >> top;
parser.str(""); // Attempting to reset the parser

parser << 6; // Input value ignored
short bottom = 0;
parser >> bottom;

In this scenario, the attempt to reset the stringstream by assigning an empty string to its str member doesn't fully clear the stream. As a result, the subsequent input value of 6 is ignored, and the second extraction operation fails.

To effectively reset a stringstream, it's necessary to not only assign an empty string to str but also clear any remaining fail and eof flags. This can be achieved using the clear method:

parser.str(std::string());
parser.clear();

By executing both of these actions, the stringstream is fully reset and ready for reuse, as the underlying sequence is emptied and all flags are cleared. Failing to perform both steps can lead to unexpected behavior, such as the stream remaining in an "end-of-file" state, causing subsequent operations to fail.

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