Checking for an empty file in C

Question

Is there an easy way to check if a file is empty   Like if you are passing a file to a function and you realize it s empty  then you close it right away   Thanks   Edit  I tried using the fseek method  but I get an error saying  cannot convert ifstream to FILE        My function s parameter is   myFunction ifstream  amp inFile

User · Answer

use this  data peek        0   I ve been searching for an hour until finaly this helped

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pFile   fopen  file    r    fseek  pFile  0  SEEK END   size ftell  pFile   if  size      fseek pFile  0  SEEK SET     do something       fclose pFile

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Ok  so this piece of code should work for you  I changed the names to match your parameter   inFile seekg 0  ios  end     if  inFile tellg      0                do something with empty file

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if  nfile eof       Prompt data from the Priming read      nfile  gt  gt  CODE  gt  gt  QTY  gt  gt  PRICE  else         used to check that the file is not empty       ofile  lt  lt   empty file     lt  lt  endl      return 1

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How about  not elegant way though    int main  int argc  char  argv           std  ifstream file      file open  example txt         bool isEmpty true       std  string line       while  file  gt  gt  line            isEmpty   false           std  cout  lt  lt  isEmpty  lt  lt  std  endl

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Perhaps something akin to   bool is empty std  ifstream amp  pFile        return pFile peek      std  ifstream  traits type  eof        Short and sweet     With concerns to your error  the other answers use C-style file access  where you get a FILE  with specific functions   Contrarily  you and I are working with C   streams  and as such cannot use those functions  The above code works in a simple manner  peek   will peek at the stream and return  without removing  the next character  If it reaches the end of file  it returns eof    Ergo  we just peek   at the stream and see if it s eof    since an empty file has nothing to peek at   Note  this also returns true if the file never opened in the first place  which should work in your case  If you don t want that   std  ifstream file  filename     if   file           file is not open    if  is empty file            file is empty       file is open and not empty

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Seek to the end of the file and check the position    fseek fileDescriptor  0  SEEK END    if  ftell fileDescriptor     0            file is empty       else           file is not empty  go back to the beginning       fseek fileDescriptor  0  SEEK SET        If you don t have the file open already  just use the fstat function and check the file size directly

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C  17 solution   include  lt filesystem gt   const auto filepath    lt path to file gt   as a std  string or std  filesystem  path   auto isEmpty    std  filesystem  file size filepath     0     Assumes you have the filepath location stored  I don t think you can extract a filepath from an std  ifstream object

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char ch  FILE  f   fopen  file txt    r     if fscanf f   c   amp ch   EOF        printf  File is Empty      fclose f

[c++] Checking for an empty file in C++

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