2.4.5 Creating an Input Stream from a String

String Input Stream

First, starting at the top of your program, you need to include sstream, the string stream library.

#include <sstream>

Next, create a string an input string stream object.

string line;
istringstream iss(line);

Now, iss can be used just like cin or a file input stream.

Three-Argument `getline` Call

We've seen the standard two-argument call to getline:

string line;
getline(cin, line); //(input stream, destination)

getline can also be called with three arguments

string token;
char delimiter = ' '; // if you want to use a space character as a delimiiter
getline(cin, token, delimiter);

getline returns the number of characters read in from the input stream, including the new line character (\n), but not including the terminating null byte (\0).

string line;
istringstream iss(line);
string token;
while (getline(iss, token, ';')) // assuming you want to use ; as a delimiter
{ 
    // read from the string
}

This works because, in C++, any non-0 number is the equivalent of true, while 0 is the equivalent of false.

Remember, true is stored as 1 and false is stored as 0 in C++!

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String Input Stream and Three-Argument getline