CFile

CFile is a C++ class that is provided to simplify 825 file operations. CFile is a wrapper class around the standard C library FILE object. CFile also provides some useful features such as baud rate setting for the 825 serial ports.

Constructors

CFile(void);
CFile(const string& strFilename);
CFile(const char* pszfilename);

These constructors just create a CFile object without opening a file.

CFile(const string& strFilename, const string& strMode);
CFile(const string& strFilename, const char* pszMode);
CFile(const char* pszFilename, const string& strMode);
CFile(const char* pszFilename, const char* pszMode);

These constructors construct the file object and attempt to open the file.

Parameters

• strFilename - filename
• pszFilename - filename
• strMode - mode
• pszMode - mode

Examples

CFile fileLog("/mnt/fl1/log.txt", "a");
if(fileLog.IsOpen())
{
     fileLog.Print("Gross %s Tare %s Net %s\r\n", FormatGrossWt(1).c_str(), FormatTareWt(1).c_str(), FormatNetWt(1).c_str()); 
     fileLog.Close();
}

CFile fileLog("/mnt/fl1/log.txt");

This contructs the object to open later.

Member Functions

Open

Opens a specified file, or using the filename already stored in the object.

bool Open(const string& strFilename, const string& strMode);
bool Open(const string& strFilename, const char* pszMode);
bool Open(const char* pszFilename, const string& strMode);
bool Open(const char* pszFilename, const char* pszMode);
bool Open(const char* pszMode);

Parameters

• strFilename - filename
• pszFilename - filename
• strMode - mode
• pszMode - mode

Return Value

Returns true if successful or false if unsuccessful.

Remarks

Example

CFile file;
if(file.Open("/tmp/tmpfile", "w") == false)
{
    DisplayText(0, 0, "Error writing temporary file");
}

Close

Closes the file

void Close(void);

Parameters

Function does not accept any parameters

Retrun Value

Function does not return any result.

Remarks

For serial ports it may be necessary to provide some delay to allow all of the buffered data to be sent out of the port before closing the port.

Example

CFile file("/dev/ttyS1", "w");
file.Print("This is a test\r\n");
SleepSeconds(1);
file.Close();

SetSerial

Set the baud rate, number of data bits, parity, and number of stop bits for serial ports.

bool SetSerial(baud_index baud, data_bit_index = data8, parity_index = parityNone, stop_bit_index = stopOne);

Parameters

• baud_index - baud1200, baud2400, baud4800, baud9600, baud19200, baud38400, baud57600, or baud115200
• data_bit_index - data7 or data8
• parity_index - parityNone, parityEven, or parityOdd
• stop_bit_index - stopOne or stopTwo

Return Value

Returns true if successful, false if not successful.

Remarks

Examples

CFile file("/dev/ttyS1", "w");
if(file.IsOpen())
{
   file.SetSerial(CFile::baud9600, CFile::data7, CFile::parityEven, CFile::stopOne);
}

CFile file("/dev/ttyS1", "w");
if(file.IsOpen())
{
   file.SetSerial(CFile::baud19200);
}

ReadLine

Reads a text file a line at a time.

bool ReadLine(string& strLine);

Parameters

• strLine - string reference to return line read

Return Value

Returns true if line read, false if end of file

Remarks

Example

CFile file("/mnt/nand/apps/test/config.txt", "r");
if(file.IsOpen())
{
   string strLine;
   while(file.ReadLine(strLine) == true)
   {
       if(strLine.substr(0, 7) == "Setting")
       {
           DisplayText(0, 0, "Found line that starts with 'Setting'");
       }
   }
   file.Close();
}

DeleteFile

Deletes a file

static bool DeleteFile(const string& strFilename);
static bool DeleteFile(const char* pszFilename);

bool DeleteFile(void);

Parameters

• strFilename - string filename to delete
• pszFilename - pointer to null terminated character array filename to delete

Return value

Returns true if successful, false if not successful.

Remarks

Versions of this fuctions that accept a filename are static so they do not require a CFile object to be created first.

Examples

string str = "/tmp/tmpfile";
CFile::DeleteFile(str);

if(CFile::DeleteFile("/tmp/tmpfile") == false)
{
   DisplayText(0, 0, "Delete file error");
}

CFile file("/tmp/tmpfile", "w");
if(file.IsOpen())
{
   file.Print("This will not exist very long\r\n");
   file.Close();
   SleepSeconds(5);
   file.DeleteFile();
}

IsOpen

Check whether the file is open

bool IsOpen(void)

Parameters

This function does not accept any parameters.

Return Value

This function returns true if the file is open, false if the file is not open

Remarks

Example

CFile file("/tmp/tmpfile", "w");
if(file.IsOpen() == false)
{
   DisplayText(0, 0, "File is not open");
}

IsReady

Check the state of the serial CTS input

bool IsReady(void);

Parameters

Function does not accept any parameters.

Return Value

Function returns true if CTS is active, false if CTS is inactive.

Remarks

IsReady() will return false if the CTS line is unconnected. Printers or other devices must be wired correctly for applications to be able to use this function to determine their readiness. The main board COM3 is not currently supported by this function.

Example

CFile fileLogOutput("/dev/ttyS1", "w");
if(fileLogOutput.IsOpen())
{
   fileLogOutput.SetRTS(true);
   if(fileLogOutput.IsReady() == false)
   {
      DisplayText(0, 0, "Printer offline, or disconnected");
   }
}

SetRTS

Set the state of the serial RTS output

bool SetRTS(bool bRTSOn = true);

Parameters

• bRTSOn - true to turn on RTS output, false to turn off RTS output

Return Value

Returns true if successfully set RTS state, false otherwise.

Remarks

Example

CFile fileLogOutput("/dev/ttyS1", "w");
fileLogOutput.SetRTS(true);

GetFile

Get the file handle of the member FILE.

FILE* GetFile(void);

Parameters

Function does not accept any parameters

Return Value

Function returns FILE handle of underlying FILE.

Remarks

Example

CFile file("/tmp/test", "w");
if(file.IsOpen())
{
   fprintf(file.GetFile(), "This is a test\r\n");
   file.Close();
}

In the above example the fprintf could be replaced with file.Print("This is a test\r\n"); eliminating the need for the GetFile() call.

Print

Outputs text which may include format specifiers. For each format specifier an additional parameter must be provided.

void Print(const string& strFormat, ...);
void Print(const char* pszFormat, ...);
void Print(const string& strFormat, va_list& args);
void Print(const char* pszFormat, va_list& args);

Parameters

• strFormat - string to output, may include format specifiers such as C printf statements
• pszFormat - pointer to null-terminated string to output, may include format specifiers
• ... - variable list of arguments that should match up with format specifiers
• args - variable list of aguments structure

Return Value

Function does not return a value.

Remarks

Examples

string str = "Hello World\r\n";
file.Print(str);

int n = 5;
string str = "ABC";
file.Print("Number: %d String %s\r\n", n, str.c_str());

// This is a function to log update data to two devices
// g_fileLog1, and g_fileLog2 are globals that should already have been opened before this function is called.
void LogOutput(const char* fmt, ...)
{
   va_list args;
   va_start(args, fmt);

   g_fileLog1.Print(fmt, args);
   g_fileLog2.Print(fmt, args);

   va_end(args);
}

SetNonBlocking

Set the file to not wait for data to arrive when reading.

void SetNonBlocking(void);

Parameters

Function does not accept any parameters

Return Value

Function does not return a value

Remarks

This is usually required for reading data from serial ports because you will not want your program to lock up waiting for data.

Example

CFile fileComm("/dev/ttyS0", "r");
if(fileComm.IsOpen())
{
   fileComm.SetNonBlocking();
   // Reads will now return whatever data is available without hanging waiting on more data.
}

Read

Reads a binary block of data from a file.

bool Read(void *pData, size_t nSize);

Parameters

• pData - pointer to memory to store data received. The application must have sufficient memory allocated.
• nSize - number of bytes to read.

Return Value

Function returns true if the specified number of bytes were read

Remarks

Example

Write

Writes a binary block of data to a file.

bool Write(void *pData, size_t nSize);

Parameters

• pData - pointer to memory to store data received. The application must have sufficient memory allocated.
• nSize - number of bytes to read.

Return Value

Function returns true if the specified number of bytes were written.

Remarks

Example

GetBytesRead

Returns how may bytes were read from previous Read function.

size_t GetBytesRead(void);

Parameters

Function does not accept any parameters.

Return Value

Function returns number of bytes read from the previous read operation.

Example

GetbytesWritten

Returns how may bytes were written from previous Write function.

size_t GetBytesWritten(void);

Parameters

Function does not accept any parameters.

Return Value

Function returns number of bytes read from the previous read operation.

Example

Seek

bool Seek(long int offset, long int origin = SEEK_SET);