Question

我写了一个文件读写器继续代码还没有完成。

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

const std::string path_to_data = "\\data";
const std::string level_file = path_to_data+"\\level_file.lev";



typedef std::string (*f_read)(std::ifstream& fin,const std::string& level_file,int    line_num);
typedef std::string (*f_write)(std::ofstream& fout,const std::string& level_file,   std::string& what_to_write,int line_num);
typedef std::string (*pt_f_manger)(f_read,f_write);



inline bool is_empty(std::ifstream& pFile){return pFile.peek() ==     std::ifstream::traits_type::eof();}
std::string file_manger(f_read,f_write);
std::string read_file(std::ifstream& fin,const std::string& level_file,int line_num);
std::string write_file(std::ofstream& fout,const std::string& level_file,std::string what_to_write, int line_num);
std::string error_handler(std::string error_type,pt_f_manger f_manger);


int main()
{
std::string error = file_manger(read_file,write_file);
std::cout<<error<<"\n";
std::cin.get();
std::cin.get();
return 0;
}

std::string file_manger(f_read f_input,f_write f_output)
{
std::string good = "good";
std::string error = "error";
std::ifstream fin;
std::ofstream fout;
std::string test = "test";
std::string output = f_output(fout,level_file,test,0);
std::string input = f_input(fin,level_file,0);
if (output != "good")
    return error;
if (input != "good")
    return error;

return good;
 }

 std::string write_file(std::ofstream& fout,const std::string& level_file, std::string&  what_to_write,int line_num)
 {
const char* level_filec = level_file.c_str();
std::ifstream fin;
fin.open(level_filec);
if (fin.is_open())
    return "failed to open "+level_file;

if (is_empty(fin))
{
    fin.close();
    fout.open(level_filec);
    if (!fout.is_open())
        return "failed to open "+level_file;

    fout<<what_to_write;
    fout.close();
    return "good";
}
int i = 0;
int num = 0;
char ch;
while (fin.good() && i != line_num)
{
    fin.get(ch);
    if (ch == '\n')
        ++num;
    ++i;
}
int pos = fin.tellg();
fin.close();
fout.open(level_filec,std::ios_base::in);
if (!fout.is_open())
    return "failed to open "+level_file;
fout.seekp(pos);
fout<<what_to_write;
fout.close();
return "good";
  }

  std::string read_file(std::ifstream& fin,const std::string& level_file,int line_num)
  {
   const char* level_filec = level_file.c_str();
std::string read;
fin.open(level_filec);
if (fin.is_open())
    return "failed to open "+level_file;

if (is_empty(fin))
{
    fin.close();
    return "file is empty";
}
int i = 0;
int num = 0;
char ch;
while (fin.good() && i != line_num)
{
    fin.get(ch);
    if (ch == '\n')
        ++num;
    ++i;
}
std::getline(fin,read);
return read;
    }

    std::string error_handler(std::string error_type,pt_f_manger f_manger)//work in progress
    {
return "good";
    }

我收到此错误

C：\ Users \ john \ Documents \ main.cpp ||在函数'int main（）'中：| C：\ Users \ john \ Documents \ main.cpp | 25 |错误：来自'std :: string（*）的无效转换（std :: ofstream＆amp;，const string＆amp;，std :: string，int）{aka std：：basic_string（*）（std :: basic_ofstream＆amp;，const std :: basic_string＆amp;，std :: basic_string，int）}'to'f_write {aka std :: basic_string（*）（std :: basic_ofstream＆amp;，const std：：basic_string＆amp;，std :: basic_string＆amp;，int）}'[-fpermissive] | C：\ Users \ john \ Documents \ main.cpp | 17 | error：初始化'std :: string file_manger（f_read，f_write）'[-fpermissive] |的参数2 || ===构建完成：2个错误，0个警告（0分0秒）=== |

我正在使用code :: blocks。

Answer 1

typedef std::string (*f_write)(
  std::ofstream& fout, const std::string& level_file,
  std::string& what_to_write, int line_num);

std::string write_file(
  std::ofstream& fout, const std::string& level_file,
  std::string what_to_write, int line_num);

你能发现差异吗？（提示：比较第三个参数的类型）。

来自'std :: string（*）的无效转换（std :: ofstream＆amp;，const string＆amp;，std :: string，int

1 个答案: