3-7-6 读取文件并替换指定字符串

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

using namespace std;

string getData(string filename) throw(std::ifstream::failure)
{
    std::ifstream streamReader(filename, std::ios::binary);
    if (!streamReader.is_open())
        throw std::ifstream::failure("file couldn't open");
    streamReader.seekg(0, std::ios::end);     // 游标移到文件结尾
    unsigned filesize = streamReader.tellg(); // 获取游标当前位置 - 文件开始位置，此处为文件大小
    char *_data = new char[filesize];         // 分配内存
    streamReader.seekg(0, std::ios::beg);     // 跳转回开始
    streamReader.read(_data, filesize);       // 读取文件
    streamReader.close();
    string data(_data);
    delete[] _data;
    return std::move(data);
}

std::string &replaceAll(std::string &context,
                        const std::string &from,
                        const std::string &to)
{
    size_t lookHere = 0;
    size_t foundHere;
    while ((foundHere = context.find(from, lookHere)) != string::npos) // find from lookHere
    {                                                                  // to avoid the string
        context.replace(foundHere, from.size(), to);                   //"to" is the substr
        lookHere = foundHere + to.size();                              // of "from"
#ifdef SHOWREPLACE
        cout << "stringNumber:" << foundHere << endl;
#endif
    }
    return context;
}

int main(int argc, char const *argv[])
{
    if (argc < 4)
        return -1;
    try
    {
        string data = getData(argv[1]);
        string from(argv[2]);
        string to(argv[3]);
        replaceAll(data, from, to);
        cout << "The replace start:" << endl;
        cout << data << endl
             << "the replace end" << endl;
    }
    catch (const std::exception &e)
    {
        std::cerr << e.what() << '\n';
    }
    return 0;
}