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FREAD()
Read characters from a binary file into a buffer variable
------------------------------------------------------------------------------
Syntax
FREAD(<nHandle>, @<cBufferVar>, <nBytes>) --> nBytes
Arguments
<nHandle> is the file handle obtained from FOPEN(), FCREATE(), or
predefined by DOS.
<cBufferVar> is the name of an existing and initialized character
variable used to store data read from the specified file. The length of
this variable must be greater than or equal to <nBytes>. <cBufferVar>
must be passed by reference and, therefore, must be prefaced by the pass-
by-reference operator (@).
<nBytes> is the number of bytes to read into the buffer.
Returns
FREAD() returns the number of bytes successfully read as an integer
numeric value. A return value less than <nBytes> or zero indicates end
of file or some other read error.
Description
FREAD() is a low-level file function that reads characters from a binary
file into an existing character variable. It reads from the file
starting at the current DOS file pointer position, advancing the file
pointer by the number of bytes read. All characters are read including
control, null, and high-order (above CHR(127)) characters.
FREAD() is similar in some respects to both FREADSTR() and FSEEK().
FREADSTR() reads a specified number of bytes from a file up to the next
null (CHR(0)) character. FSEEK() moves the file pointer without
reading.
If there is an error during the file read, FERROR() returns the DOS
error number. See FERROR() for the list of error numbers.
Warning! This function allows low-level access to DOS files and
devices. It should be used with extreme care and requires a thorough
knowledge of the operating system.
Examples
. This example uses FREAD() after successfully opening a file to
read 128 bytes into a buffer area:
#define F_BLOCK 128
//
cBuffer := SPACE(F_BLOCK)
nHandle := FOPEN("Temp.txt")
//
IF FERROR() != 0
? "File open error:", FERROR()
ELSE
IF FREAD(nHandle, @cBuffer, F_BLOCK) <> F_BLOCK
? "Error reading Temp.txt"
ENDIF
FCLOSE(nHandle)
ENDIF
Files Library is CLIPPER.LIB.
See Also:
BIN2I()
BIN2L()
BIN2W()
FCLOSE()
FCREATE()
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