I/O流类库（四）

字符串流

• istringstream，由istream派生而来，提供读string的功能
• ostringstream，由ostream派生而来，提供些string的功能
• stringstream，由iostream派生而来，提供读写string的功能

istringstream

#include <iostream>
#include<sstream>

using namespace std;

int main(void)
{
    string line;
    string word;
    while (getline(cin, line))
    {
        istringstream iss(line);
        while (iss >> word)
            cout << word << "#";
        cout << endl;
    }
}

ostringstream

#include <iostream>
#include<sstream>

using namespace std;
string Double2Str(double& val)
{
    ostringstream oss;
    oss << val;
    return oss.str();
}
double Str2Double(const string& str)
{
    istringstream iss(str);
    double val;
    iss >> val;
    return val;
}
int main(void)
{
    double val = 55.55;
    string str = Double2Str(val);
    cout << str << endl;

    str = "123.123";
    val = Str2Double(str);
    cout << val << endl;
    return 0;
}

/*-------------------例-----------------------------*/
#include <iostream>
#include<sstream>

using namespace std;

int main(void)
{
    istringstream iss("192,168,0,100");
    cout << iss.str() << endl;
    int v1, v2, v3, v4;
    char ch;
    iss >> v1 >> ch >> v2 >> ch >> v3 >> ch >> v4;
    ostringstream oss;
    ch = '.';
    oss << v1 << ch << v2 << ch << v3 << ch << v4;
    cout << oss.str() << endl;
    return 0;
}