用C ++读取多个.dat文件

时间:2013-03-23 03:57:44

标签: c++

我使用下面的代码读取一个.dat文件并找到执行时间,它运行得很好。我试图建立一个循环来读取多个文件,因为我有超过20个具有不同名称的文件(我需要保留他们的名字),但它没有用。如何开发此代码以读取位于某个文件夹中的所有文件,无论它们有多少? (基于以下代码)

#include <Windows.h>
#include <ctime>
#include <stdint.h>
#include <iostream>
using std::cout;
using std::endl;
#include <fstream>
using std::ifstream;

#include <cstring>

/* Returns the amount of milliseconds elapsed since the UNIX epoch. Works on both
 * windows and linux. */

uint64_t GetTimeMs64()
{


 FILETIME ft;
 LARGE_INTEGER li;

 /* Get the amount of 100 nano seconds intervals elapsed since January 1, 1601 (UTC) and copy it
  * to a LARGE_INTEGER structure. */
 GetSystemTimeAsFileTime(&ft);
 li.LowPart = ft.dwLowDateTime;
 li.HighPart = ft.dwHighDateTime;

 uint64_t ret;
 ret = li.QuadPart;
 ret -= 116444736000000000LL; /* Convert from file time to UNIX epoch time. */
 ret /= 10000; /* From 100 nano seconds (10^-7) to 1 millisecond (10^-3) intervals */

 return ret;

}




const int MAX_CHARS_PER_LINE = 512;
const int MAX_TOKENS_PER_LINE = 20;
const char* const DELIMITER = "|";

int main()
{
  // create a file-reading object
  ifstream fin;
  fin.open("promotion.txt"); // open a file
  if (!fin.good()) 
    return 1; // exit if file not found

  // read each line of the file
  while (!fin.eof())
  {
    // read an entire line into memory
    char buf[MAX_CHARS_PER_LINE];
    fin.getline(buf, MAX_CHARS_PER_LINE);

    // parse the line into blank-delimited tokens
    int n = 0; // a for-loop index

    // array to store memory addresses of the tokens in buf
    const char* token[MAX_TOKENS_PER_LINE] = {}; // initialize to 0

    // parse the line
    token[0] = strtok(buf, DELIMITER); // first token
    if (token[0]) // zero if line is blank
    {
      for (n = 1; n < MAX_TOKENS_PER_LINE; n++)
      {
    token[n] = strtok(0, DELIMITER); // subsequent tokens
        if (!token[n]) break; // no more tokens
  }
}

    // process (print) the tokens
    for (int i = 0; i < n; i++) // n = #of tokens
      cout << "Token[" << i << "] = " << token[i] << endl;
    cout << endl;
  }
  uint64_t z = GetTimeMs64();
  cout << z << endl;
  system("pause");
}

3 个答案:

答案 0 :(得分:1)

要列出Windows上目录中的文件,请参阅以下链接:

http://msdn.microsoft.com/en-us/library/windows/desktop/aa365200(v=vs.85).aspx

关于您的代码的说明:

  1. 请勿使用fin.eof()来测试输入的结尾,请参阅原因:eof of istream in C++

  2. 要阅读多个文件,如果您使用相同的fin.clear()来阅读多个文件,请在fin.close之前记住fin

  3. 更新:

    以下代码在目录D:\\Test中打印出文件名。如果您需要子文件夹中的每个文件或文件的绝对路径,请更改GetFiles来执行此操作。根据我提供的链接,这非常简单。代码在VS2012 Win7 Pro上进行测试。

    #include <windows.h>
    #include <Shlwapi.h>
    
    #include <iostream>
    #include <fstream>
    #include <string>
    #include <vector>
    using namespace std;
    
    #pragma comment(lib, "Shlwapi.lib")
    
    int GetFiles(const string &path, vector<string> &files, const string &wildcard = "\\*")
    {
        wstring basepath(path.begin(), path.end());
        wstring wpath = basepath + wstring(wildcard.begin(), wildcard.end());
    
        WIN32_FIND_DATA ffd;
        HANDLE hFind = INVALID_HANDLE_VALUE;
        DWORD dwError = 0;
    
        hFind = FindFirstFile(wpath.c_str(), &ffd);
    
        if (INVALID_HANDLE_VALUE == hFind) {
            // display error messages
            return dwError;
        }
    
        TCHAR buf[MAX_PATH];
        do {
            if (ffd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
                // directory
            } else {
                PathCombine(buf, basepath.c_str(), ffd.cFileName);
                wstring tmp(buf);
                files.push_back(string(tmp.begin(), tmp.end()));
            }
        } while (FindNextFile(hFind, &ffd));
    
        dwError = GetLastError();
        if (ERROR_NO_MORE_FILES != dwError) {
            // some errors
        }
        FindClose(hFind);
        return dwError;
    }
    
    int main()
    {
        string path("D:\\Documents\\Visual Studio 2012\\Projects\\SigSpatial2013");
        vector<string> files;
        GetFiles(path, files);
        string line;
        ifstream fin;
        for (int i = 0; i < files.size(); ++i) {
            cout << files[i] << endl;
    
            fin.open(files[i].c_str());
            if (!fin.is_open()) {
                // error occurs!!
                // break or exit according to your needs
            }
    
            while (getline(fin, line)) {
                // now process every line
            }
    
            fin.clear();
            fin.close();
        }
    }
    

答案 1 :(得分:1)

我认为这更容易:

1-如果您将读取文件并将其内容处理成自己的函数的代码分解出来:
void process_file( char* filename );
2-添加一个新功能列出目录的内容:char** list_dir( char* dir );
3-组合主()中的2个功能()

这使得代码更清晰,更易于测试

答案 2 :(得分:1)

我同意封装此内容的建议。 在Windows上,代码看起来像这样

HANDLE h;
WIN32_FIND_DATA find_data;
h = FindFirstFile( "*.dat", & find_data );
if( h == INVALID_HANDLE_VALUE ) {
    // Error
    return;
}
do {
    char * s = find_data.cFileName;
            // Your code here
} while( FindNextFile( h, & find_data ) );
FindClose( h );