FileWriteDouble - MQL4 Documentation

MQL4 Reference File functions FileWriteDouble

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int FileWriteDouble(

int handle, double value, int size=DOUBLE_VALUE)

The function writes a double value with floating point to a binary file. If the format is specified as FLOAT_VALUE, the value will be written as a 4-bytes floating point number (of the float type), otherwise, it will be written in the 8-bytes floating point format (of the double type).
Returns the actually written bytes count or a negative value if an error occurs.
To get the detailed error information, one has to call the GetLastError() function.

Parameters:

handle	-	File handle returned by the FileOpen() function.
value	-	Double precision value.
size	-	Optional format flag. It can be any of the following values: DOUBLE_VALUE (8 bytes, default) FLOAT_VALUE (4 bytes).

Sample:

  int handle;
  double var1=0.345;
  handle=FileOpen("mydata.dat", FILE_BIN|FILE_WRITE);
  if(handle<1)
    {
     Print("can't open file error-",GetLastError());
     return(0);
    }
  FileWriteDouble(h1, var1, DOUBLE_VALUE);
  //...
  FileClose(handle);

FileWriteArray FileWriteInteger