Demonstrating istringstream

Figure 19.12 demonstrates input from an istringstream object. Lines 10–11 create string input containing the data and istringstream object inputString constructed to contain the data in string input. The string input contains the data

Input test 123 4.7 A

which, when read as input to the program, consist of two strings ("Input" and "test"), an int (123), a double (4.7) and a char ('A'). These characters are extracted to variables string1, string2, integer, double1 and character in line 18.

Click here to view code image

 1   // Fig. 19.12: Fig19_12.cpp
 2   // Demonstrating input from an istringstream object.
 3   #include <iostream>
 4   #include <string>
 5   #include <sstream>      
 6   using namespace std;
 7
 8   int main()
 9   {
10      string input( "Input test 123 4.7 A" );
11      istringstream inputString( input );
12      string string1;
13      string string2;
14      int integer;
15      double double1;
16      char character;
17
18      inputString >> string1 >> string2 >> integer >> double1 >> character;
19
20      cout << "The following items were extracted "
21         << "from the istringstream object:" << " string: " << string1
22         << " string: " << string2 << "    int: " << integer
23         << " double: " << double1 << "   char: " << character;
24
25      // attempt to read from empty stream
26      long value;
27      inputString >> value;
28
29      // test stream results
30      if ( inputString.good() )
31         cout << " long value is: " << value << endl;
32      else
33         cout << " inputString is empty" << endl;
34   } // end main

The following items were extracted
from the istringstream object:
string: Input
string: test
   int: 123
double: 4.7
  char: A

inputString is empty

Fig. 19.12. Demonstrating input from an istringstream object.

The data is then output in lines 20–23. The program attempts to read from inputString again in line 27. The if condition in line 30 uses function good (Section 13.8) to test if any data remains. Because no data remains, the function returns false and the else part of the if...else statement is executed.

Image
..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset
3.133.137.169