【cpp】chap 8

1.输出“输入的内容”

// basic file operations
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

std::istream& func(std::istream &is)
{
    std::string buf;
    while (is >> buf)
        std::cout << "output = " << buf << std::endl;
    is.clear();
    return is;
}

int main() {
    std::istream &is=cin;
    func(is);
}

2.istringstream

#include <iostream>
#include <sstream>
using std::istream;

istream& func(istream &is)
{
    std::string buf;
    while (is >> buf)
        std::cout << buf << std::endl;
    is.clear();
    return is;
}

int main()
{
    std::istringstream iss("hello");
    func(iss);

    system("pause");
    return 0;
}

3.ReadFileToVec——将每一行储存成为vector元素

#include <fstream>
#include <string>
#include <vector>
#include <iostream>

using std::vector; using std::string; using std::ifstream; using std::cout; using std::endl;

void ReadFileToVec(const string& fileName, vector<string>& vec)
{
    ifstream ifs(fileName);
    if (ifs)
    {
        string buf;
        while (std::getline(ifs, buf))
            vec.push_back(buf);
    }
}

int main()
{
    vector<string> vec;
    ReadFileToVec("cww.txt", vec);
    for (const auto &str : vec)
        cout << str << endl;
    system("pause");
    return 0;
}

将每个单词存储到vector元素：

#include <fstream>
#include <string>
#include <vector>
#include <iostream>

using std::vector; using std::string; using std::ifstream; using std::cout; using std::endl;

void ReadFileToVec(const string& fileName, vector<string>& vec)
{
    ifstream ifs(fileName);
    if (ifs)
    {
        string buf;
        while (ifs >> buf)
            vec.push_back(buf);
    }
}

int main()
{
    vector<string> vec;
    ReadFileToVec("cww.txt", vec);
    for (const auto &str : vec)
        cout << str << endl;
    system("pause");
    return 0;
}

4.除非有必须使用其他容器的理由，否则就用Vector或List。