Demonstrate string streams
#include <iostream>
#include <sstream>
using namespace std;
int main()
{
stringstream s("This is initial string.");
// get string
string str = s.str();
cout << str << endl;
// output to string stream
s << "Numbers: " << 10 << " " << 123.2;
int i;
double d;
s >> str >> i >> d;
cout << str << " " << i << " " << d;
return 0;
}This is initial string.
Numbers: 10 123.2
stringstream::str( empty string): Empty the string
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
using namespace std;
int main( ) {
stringstream ss;
ss << "string " << 9 << 1.2;
cout << ss.str( ) << endl;
ss.str(""); // Empty the string
cout << ss.str( ) << endl;
}string 91.2
stringstream::str( ) returns a string
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
using namespace std;
int main( ) {
stringstream ss;
ss << "string " << 9 << 1.2;
cout << ss.str( ) << endl; // stringstream::str( ) returns a string
}string 91.2
Use stringstream to parse a number
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
double parse(const string& str) {
stringstream ss(str);
double d = 0;
ss >> d;
if (ss.fail( )) {
throw (str +" is not a number");
}
return (d);
}
int main( ) {
try {
cout << parse("1.234e5") << endl;
cout << parse("6.02e-2") << endl;
cout << parse("asdf") << endl;
}
catch (string& e) {
cerr << e << endl;
}
}123400
0.0602
asdf is not a number
