Checkpoint 11.10.1.
Construct a block of code that uses a string stream to break
"April 22 2025" into the string "April" and the integers 25 and 2025.
Section 11.10 String Streams
One final kind of stream is worth discussion: the
stringstream. This is a stream that reads from or writes to a string. It can be used as an alternative to std::format for building up a string with data from variables. It also can be used to imitate writing to a file. If we want to test out code that is supposed to write to a file, we can instead have it write to a stringstream and then print out the string that was produced. If the output looks good, we know that if we successfully open a file and write to that instead of the stringstream, our program should work correctly.
The
stringstream data type is defined in the <sstream> library. Once we create a variable of type stringstream we can then immediately write to it using << (there is no file to open). Once we are done writing, we can use the .str() method to ask the string stream for the string that was built up:
It is also possible to read from a string stream. This is done by using the
.str() method to set the string that we want to read from. Once we have set the string, we can use >> to read from it just like we would from a file or the console:
Notice that once we are done setting up the stringstream, all the rest of the code looks just like reading from a file. We even still use
eof() even though there isn’t really a file that we are reading from. This is the advantage of using the “stream” abstraction—we can use one set of tools to read from the console, a file, or a stringstream all in the same way.
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