we are running into an odd issue when trying to parse an input file. the idea is that this file can include other files, which must be parsed as well. We are doing this recursively in a function defined as
int parse_inp(const char* filename)
The main file parses no problem, but recursive calls cannot open their file streams.
int parse_inp(const char* filename)
{
char buffer[BUFFER_MAX+1];
char* token;
std::string tok;
int keywordSection;
bool end_of_file;
int cardNum;
...
int i;
std::string tempop;
double tempd1, tempd2;
SetSegmentCard2 tempSetSegmentCard2;
int offset;
printf("%s\n", filename);
std::ifstream inp;
inp.clear();
inp.open(filename, std::ios::in);
if(!inp.good() || !inp.is_open())
{
char path1[256];
getcwd(path1,256);
printf("CWD: %s\n", path1);
fflush(NULL);
printf("Unable to open '%s'\n", filename);
return 0;
}
std::set<std::string> unrecognized;
std::string line;
while(inp.good() && !inp.eof())
{
getline(inp, line);
strcpy(buffer, line.c_str());
if (isComments(buffer)) //skip the comments line
continue;
if (buffer[0]=='*') //this is a keyword line
{
token = strtok(buffer," \n");
keywordSection = is_inp_keyw(token);
if (keywordSection==0)
unrecognized.insert(token);
cardNum = 0;
continue;
}
//a data line
tempop="";
char* found = NULL;
char path_buffer[100] = "Dyna3DWriter\\";
int pos = 0;
switch(keywordSection)
{
case 0: //not recognized
//end of last keyword, not recognizable word
break;
case 1: //KEYWORD
//"KEYWORD didn't do anything
break;
case 2: //TITLE
break;
case 3: //INCLUDE
token = strtok(buffer, "\n");
inp.clear();
parse_inp(token);
break;
...
}
}
if(inp.is_open())
{
inp.close();
inp.clear();
}
}
The recursive files never parse. I looked around a lot and most issues seemed to be either that the fail bit was set (which is why we are calling inp.clear() a lot), or that we are making the wrong assumption about the current working directory.
To test the second theory, we added in:
if(!inp.good() || !inp.is_open())
{
char path1[256];
getcwd(path1,256);
printf("CWD: %s\n", path1);
fflush(NULL);
printf("Unable to open '%s'\n", filename);
return 0;
}
And our working directory and file name are both correct. We see the same behavior when using fopen(filename, "r") --- a call to perror("fopen") results in:
fopen: no such file or directory
EDIT: Filled in more code
Are you sure the filename does not contain any garbage or bad character that would lead to this issue?
If the error is file not found, that means the filename is wrong in some way.
Could it come from a bad declaration of buffer? We don't see it in your code.
Another possibility is that you use strtok again in your initialization before opening the file. You must avoid using strtok that is based on global storage for recursive method like this. You should use strtok_r instead.
If your recursive function is called very deeply you can easily overload the OS limit on the number of open files.
I used to run my Gentoo Linux with a per-process file limit of 250 with exceptions for programs that needed a lot more.
Windows has limits that vary depending on how much memory is available to the system and how many objects have already been created system-wide.
The smart way to do this is to have two functions. The first function is the one everyone else calls and it does the setup, including opening the file. The second function is the recursive function and it takes nothing but a reference to a std::ifstream object.
EDIT:
I see that I misunderstood your question, and you aren't recursively opening the same file. I will leave my above paragraph anyway.
Related
I actually need my driver to read (line by line) some programs that are going to be blacklisted.
_T("bannedfile.exe") is where I actually need to put the blacklisted program.
How can I make _tcscmp read a text file, line by line?
(It makes a comparison between the host program that loads the driver, and the blacklisted one)
BOOL ProcessBlackList() {
TCHAR modulename[MAX_PATH];
GetModuleFileName(NULL, modulename, MAX_PATH);
PathStripPath(modulename);
if (_tcscmp(modulename, _T("bannedfile.exe")) != 1) {
return 0;
}
else {
return 0x2;
}
}
Can't be done that way.
You should be able to use use getline to read the file line by line and then pass the lines to _tcscmp. Should work something like this:
wchar_t const name[] = L"bannedfile.exe";
std::wifstream file(name);
std::wstring line;
while (std::getline(file, line)
{
if (_tcscmp(modulename, line.c_str()) == 0) {
return TRUE; //module is in list
}
}
return FALSE; // module is not in list
Lacking a copy of VS to test it at the moment.
If you run into unicode parsing problems because the file's encoding isn't quite what the defaults expect, give this a read: What is std::wifstream::getline doing to my wchar_t array? It's treated like a byte array after getline returns
I wrote the following method to check whether my program works correctly with file IO, but it most definitely doesn't work. All that I get from inFile is "ELF", can anyone tell me why? My objects work perfectly fine with other types of istreams.
void testFiles(int ct, char ** args)
{
if(ct<2){
cout<<"Invalid number of arguments. Must be two files, one for input, one for output."<<endl;
return;
}
ifstream inFile;
inFile.open(args[0]);
Tree<Word,int> x;
Word *key;
Word *val;
cout<<"Tree extracted from file: "<<endl;
while(inFile.good()&&inFile.is_open()){
key = new Word();
val = new Word();
inFile>>*key;
inFile>>*val;
if(!inFile.good()){
cout<<"Error: incomplete key-value pair:"<<key->getStr()<<endl;
break;
}
cout<<key->getStr()<<" "<<val->getStr()<<endl;
x[*key] = val->asInt();
delete key;
delete val;
}
inFile.close();
ofstream outFile;
outFile.open(args[1]);
cout<<"Tree as read from file:"<<endl<<x;
outFile<<x;
outFile.close();
}
args[0] is not the first argument to your program. It's the name of the executable file itself.
What's happening is that you're opening your own executable file, rather than the file specified on the command line, and since your program is a linux binary, you're reading in the magic string at the start of ELF binaries, which is "ELF".
To fix the error, change args[0] to args[1].
You are specifying the program name instead of the first param as a file name.
It is a good idea to check for the validity of what U do. ie. check either whether the args[1] is not empty and/or the return value of file open... Only checking the parameter count is not enough.
I want to alternate between reading multiple files. Below is a simplified version of my code.
ifstream* In_file1 = new ifstream("a.dat", ios::binary);
ifstream* In_file2 = new ifstream("b..dat", ios::binary);
ifstream* In_file;
int ID;
In_file = In_file1;
int ID = 0;
//LOOPING PORTION
if (In_file -> eof())
{
In_file -> seekg(0, ios_base::beg);
In_file->close();
switch (ID)
{
case 0:
In_file = In_file2; ID = 1; break;
case 1:
In_file = In_file1; ID = 0; break;
}
}
//some codes
:
:
In_file->read (data, sizeof(double));
//LOOPING PORTION
The code works well if I am reading the files one time and I thought that everything was cool. However, if the part termed 'looping portion' is within a loop, then the behaviour becomes weird and I start having a single repeating output. Please, can someone tell me what is wrong and how I can fix it? If you have a better method of tacking the problem, please suggest. I appreciate it.
//SOLVED
Thank you everybody for your comments, I appreciate it. Here is what I simple did:
Instead of the original
switch (ID)
{
case 0:
In_file = In_file2; ID = 1; break;
case 1:
In_file = In_file1; ID = 0; break;
}
I simply did
switch (ID)
{
case 0:
In_file = new ifstream("a.dat", ios::binary); ID = 1; break;
case 1:
In_file = new ifstream("b.dat", ios::binary); ID = 0; break;
}
Now it works like charm and I can loop as much as I want:-). I appreciate your comments, great to know big brother still helps.
Let's see: the code you posted works fine, and you want us to tell you
what's wrong with the code you didn't post. That's rather difficult.
Still, the code you posted probably doesn't work correctly either.
std::istream::eof can only be used reliably after an input (or some
other operation) has failed; in the code you've posted, it will almost
certainly be false, regardless.
In addition: there's no need to dynamically allocate ifstream; in
fact, there are almost no cases where dynamic allocation of ifstream
is appropriate. And you don't check that the opens have succeeded.
If you want to read two files, one after the other, the simplest way is
to use two loops, one after the other (calling a common function for
processing the data). If for some reason that's not appropriate, I'd
use a custom streambuf, which takes a list of filenames in the
constructor, and advances to the next whenever it reaches end of file on
one, only returning EOF when it has reached the end of all of the
files. (The only complication in doing this is what to do if one of the
opens fails. I do this often enough that it's part of my tool kit,
and I use a callback to handle failure. For a one time use, however,
you can just hard code in whatever is appropriate.)
As a quick example:
// We define our own streambuf, deriving from std::streambuf
// (All istream and ostream delegate to a streambuf for the
// actual data transfer; we'll use an instance of this to
// initialize the istream we're going to read from.)
class MultiFileInputStreambuf : public std::streambuf
{
// The list of files we will process
std::vector<std::string> m_filenames;
// And our current position in the list (actually
// one past the current position, since we increment
// it when we open the file).
std::vector<std::string>::const_iterator m_current;
// Rather than create a new filebuf for each file, we'll
// reuse this one, closing any previously open file, and
// opening a new file, as needed.
std::filebuf m_streambuf;
protected:
// This is part of the protocol for streambuf. The base
// class will call this function anytime it needs to
// get a character, and there aren't any in the buffer.
// This function can set up a buffer, if it wants, but
// in this case, the buffering is handled by the filebuf,
// so it's likely not worth the bother. (But this depends
// on the cost of virtual functions---without a buffer,
// each character read will require a virtual function call
// to get here.
//
// The protocol is to return the next character, or EOF if
// there isn't one.
virtual int underflow()
{
// Get one character from the current streambuf.
int result = m_streambuf.sgetc();
// As long as 1) the current streambuf is at end of file,
// and 2) there are more files to read, open the next file
// and try to get a character from it.
while ( result == EOF && m_current != m_filenames.eof() ) {
m_streambuf.close();
m_streambuf.open( m_current->c_str(), std::ios::in );
if ( !m_streambuf.is_open() )
// Error handling here...
++ m_current;
result = m_streambuf.sgetc();
}
// We've either gotten a character from the (now) current
// streambuf, or there are no more files, and we'll return
// the EOF from our last attempt at reading.
return result;
}
public:
// Use a template and two iterators to initialize the list
// of files from any STL sequence whose elements can be
// implicitly converted to std::string.
template<typename ForwardIterator>
MultiFileInputStreambuf(ForwardIterator begin, ForwardIterator end)
: m_filenames(begin, end)
, m_current(m_filenames.begin())
{
}
};
#include <iostream>
#include <fstream>
#include <string>
#define NO_OF_FILES 2
int main ()
{
std::ifstream in;
std::string line;
std::string files[NO_OF_FILES] =
{
"file1.txt",
"file2.txt",
};
// start our engine!
for (int i = 0; i < NO_OF_FILES; i++)
{
in.open(files[i].c_str(), std::fstream::in);
if (in.is_open())
{
std::cout << "reading... " << files[i] << endl;
while (in.good())
{
getline(in, line);
std::cout << line << std::endl;
}
in.close();
std::cout << "SUCCESS" << std::endl;
}
else
std::cout << "Error: unable to open " + files[i] << std::endl;
}
return 0;
}
I've got a problem with deleting/overwriting a file using my program which is also being used(read) by my program. The problem seems to be that because of the fact my program is reading data from the file (output.txt) it puts the file in a 'in use' state which makes it impossible to delete or overwrite the file.
I don't understand why the file stays 'in use' because I close the file after use with fclose();
this is my code:
bool bBool = true
while(bBool){
//Run myprogram.exe tot generate (a new) output.txt
//Create file pointer and open file
FILE* pInputFile = NULL;
pInputFile = fopen("output.txt", "r");
//
//then I do some reading using fscanf()
//
//And when I'm done reading I close the file using fclose()
fclose(pInputFile);
//The next step is deleting the output.txt
if( remove( "output.txt" ) == -1 ){
//ERROR
}else{
//Succesfull
}
}
I use fclose() to close the file but the file remains in use by my program until my program is totally shut down.
What is the solution to free the file so it can be deleted/overwrited?
In reality my code isn't a loop without an end ; )
Thanks in advance!
Marco
Update
Like ask a part of my code which also generates the file 'in use'. This is not a loop and this function is being called from the main();
Here is a piece of code:
int iShapeNr = 0;
void firstRun()
{
//Run program that generates output.txt
runProgram();
//Open Shape data file
FILE* pInputFile = NULL;
int iNumber = 0;
pInputFile = fopen("output.txt", "r");
//Put all orientations of al detected shapes in an array
int iShapeNr = 0;
int iRotationBuffer[1024];//1024 is maximum detectable shapes, can be changed in RoboRealm
int iXMinBuffer[1024];
int iXMaxBuffer[1024];
int iYMinBuffer[1024];
int iYMaxBuffer[1024];
while(feof(pInputFile) == 0){
for(int i=0;i<9;i++){
fscanf(pInputFile, "%d", &iNumber);
fscanf(pInputFile, ",");
if(i == 1) {
iRotationBuffer[iShapeNr] = iNumber;
}
if(i == 3){//xmin
iXMinBuffer[iShapeNr] = iNumber;
}
if(i == 4){//xmax
iXMaxBuffer[iShapeNr] = iNumber;
}
if(i == 5){//ymin
iYMinBuffer[iShapeNr] = iNumber;
}
if(i == 6){//ymax
iYMaxBuffer[iShapeNr] = iNumber;
}
}
iShapeNr++;
}
fflush(pInputFile);
fclose(pInputFile);
}
The while loop parses the file. The output.txt contains sets of 9 variables, the number of sets is unknown but always in sets of 9.
output.txt could contain for example: 0,1,2,3,4,5,6,7,8,8,7,6,5,4,1,2,3,0
update 2
code:
void runProgram(){
//Check if output.txt exists, if so delete it
if(fileExists("output.txt") == 1){
//Delete output.txt
if( remove( "output2.txt" ) == -1 ){
//errormessage
}else{
//succesfull
}
}
//start program
ShellExecute( NULL, TEXT("open"), TEXT("program.exe"), NULL, NULL, SW_SHOWMAXIMIZED);
while(fileExists("output.txt") == 0);
//Close program
int iCheck = system("taskkill /IM program.exe");
if(iCheck != 0){
//error could not shut down
}
}
sorry for using pre again but I don't get the formatting of this site :(
Will it be due to maximum disk space has been reached and there's still data in the file
streams buffer; fclose'ing a file stream flushes it (writes all the data in the buffer), the write operation will fail since maximum disk space is reached.
I suggest you to scope down the problem, by calling fclose() directly after fopen().
If it success, then something is wrong in the code between fclose() and fopen().
There is probably other places in your code where you don't call fclose, leaking the file. Even in this code, if an error occurs between fopen and fclose (or a return statement, or a continue statement, etc...) you'll leak the file. Please, switch to RAII idiom.
Edit: include this into your code:
struct PoorMansFile {
FILE *_file;
PoorMansFile(const char* str1, const char* str2) : _file(fopen(str1,str2)) {}
~PoorMansFile() { if(_file) fclose(_file); }
operator FILE*() const { return _file; }
};
int fclose(PoorMansFile& file)
{
if(!file)
return 0;
int t = fclose(file._file);
file._file = 0;
return t;
}
and replace each
FILE* file = NULL;
file = fopen(str1, str2);
with:
PoorMansFile file(str1, str2);
Tell us if it helps;
The file could still be in use by the CRT or OS - for example, the OS may buffer writes to the disk. fflush() will only flush CRT buffers, not OS buffers.
Just a shot in the dark here...
What is inside runProgram()? Does that function wait until the program has finished before returning? I wonder if the program that is writing the data is, in fact, still running... it's difficult to tell from here, but thought I'd throw it out there!
After reading all answers and comments I could not think of any reason of OP's problem.
Is this multi threaded or reentrant routine?
What will happen if fopen twice and fclose twice on the same file? Is this could be the cause of the problem?
In this thought I suggest two more checks.
printf all fopen/fclose call
after fclose reset file variable to NULL
f = fopen("", ""); printf("fopen => %p", f);
fclose(f); printf("fclose => %p", f); f = 0;
If you are inconvenient with printf debugging you can use OutputDebugString.
extern void __stdcall OutputDebugStringA(const char*) (MS VC only)
I am currently developing an application, which gets the input from a text file and proceeds accordingly. The concept is the input file will have details in this fomat
A AND B
B OR C
Each and every line will be seperated by a blank space and the input must be taken from the text file and processed by logic. I use a TCPP compiler and i am facing problems reading the input. Please help me with the issue...
Reading input a line at a time is normally done with std::getline, something like this:
std::string line;
std::ifstream infile("filename");
while (std::getline(line, infile))
// show what we read
std::cout << line << "\n";
If you're having trouble with things like this, you might consider looking for a (better) book on C++ than whatever you're now (hopefully) using.
Following can be used straightaway:
BOOL ReadFile(CString filename)
{
BOOL bRead = TRUE;
std::ifstream m_strmFile;
m_strmFile.open(filename, std::ios::in);
char pszLine[256];
memset(pszLine, 256, 0);
if (m_strmFile)
{
// Read whatever number of lines in your file
for (unsigned int i = 0; i < 5/*number of lines*/; i++)
m_strmFile.getline(pszLine, 256);
// Do whatever you want to do with your read lines here...
}
else bRead = FALSE;
return bRead;
}
are you using headr files like:
include
or #include and you can make use of the fileobject.getline(), (do check its proper syntax.) function in C++ or for char by char use fileobject.get(ch) kind of function