我有一個2884765579字節文件。這雙具有這種功能,它返回數檢查:seekg()神祕失敗
size_t GetSize() {
const size_t current_position = mFile.tellg();
mFile.seekg(0, std::ios::end);
const size_t ret = mFile.tellg();
mFile.seekg(current_position);
return ret;
}
我然後執行:
mFile.seekg(pos, std::ios::beg);
// pos = 2883426827, which is < than the file size, 2884765579
此設置failbit。 errno
未更改。我可以採取哪些措施來解決此問題?
我絕對相信說:
- 的文件大小是真的2884765579
pos
真的2884765579- 的failbit未.seekg之前設置()
- 失敗位在.seekg()後面設置,並且在 ,之間沒有其他調用10
- 打開文件與二進制標誌
編輯:萬一有人運行到同樣的問題..使用此代碼,我寫了許多頭痛少(僅在Windows工作)爲您:
class BinaryIFile
{
public:
BinaryIFile(const string& path) : mPath(path), mFileSize(0) {
mFile = open(path.c_str(), O_RDONLY | O_BINARY);
if (mFile == -1)
FATAL(format("Cannot open %s: %s") % path.c_str() % strerror(errno));
}
~BinaryIFile() {
if (mFile != -1)
close(mFile);
}
string GetPath() const { return mPath; }
int64 GetSize() {
if (mFileSize)
return mFileSize;
const int64 current_position = _telli64(mFile);
_lseeki64(mFile, 0, SEEK_END);
mFileSize = _telli64(mFile);
_lseeki64(mFile, current_position, SEEK_SET);
return mFileSize;
}
int64 Read64() { return _Read<int64>(); }
int32 Read32() { return _Read<int32>(); }
int16 Read16() { return _Read<int16>(); }
int8 Read8() { return _Read<int8>(); }
float ReadFloat() { return _Read<float>(); }
double ReadDouble() { return _Read<double>(); }
void Skip(int64 bytes) { _lseeki64(mFile, bytes, SEEK_CUR); }
void Seek(int64 pos) { _lseeki64(mFile, pos, SEEK_SET); }
int64 Tell() { return _telli64(mFile); }
template <class T>
T Read() { return _Read<T>(); }
void Read(char *to, size_t size) {
const int ret = read(mFile, (void *)to, size);
if ((int)size != ret)
FATAL(format("Read error: attempted to read %d bytes, read() returned %d, errno: %s [we are at offset %d, file size is %d]") % size % ret % strerror(errno) % Tell() % GetSize());
}
template <class T>
BinaryIFile& operator>>(T& val) { val = _Read<T>(); return *this; }
private:
const string mPath;
int mFile;
int64 mFileSize;
template <class T>
T _Read() { T ret; if (sizeof(ret) != read(mFile, (void *)&ret, sizeof(ret))) FATAL("Read error"); return ret; }
};
'pos'是什麼類型? – jamesdlin 2010-03-07 03:05:22
現在真正的問題是:你如何在Windows上獲得64位文件位置(除了切換到64位操作系統)。我無法幫到那裏,對不起。 – Tronic 2010-03-07 03:10:06
是的,那是你的問題。帶有一個參數的'seekg'需要一個'streampos'參數,'seekg'有兩個'streamoff'參數。後者必須簽名。 – jamesdlin 2010-03-07 03:13:09