fread_bytesT_fread_bytesFreadBytesFreadBytesfread_bytes (Operator)

Name

fread_bytesT_fread_bytesFreadBytesFreadBytesfread_bytes — Read bytes from a binary file.

Signature

fread_bytes( : : FileHandle, NumberOfBytes : ReadData, IsEOF)

Description

The operator fread_bytesfread_bytesFreadBytesFreadBytesFreadBytesfread_bytes reads bytes from the input file defined by FileHandleFileHandleFileHandleFileHandlefileHandlefile_handle. The input file must have been opened with open_fileopen_fileOpenFileOpenFileOpenFileopen_file in binary format.

The number of bytes to be read, greater than 0, is specified as NumberOfBytesNumberOfBytesNumberOfBytesNumberOfBytesnumberOfBytesnumber_of_bytes.

The bytes that are read are returned in ReadDataReadDataReadDataReadDatareadDataread_data. IsEOFIsEOFIsEOFIsEOFisEOFis_eof is set to 1 if end of file is reached while reading the bytes from the input binary file. Otherwise, it is set to 0.

When the number of bytes to be read is larger than the number of bytes in the input binary file, the operator fread_bytesfread_bytesFreadBytesFreadBytesFreadBytesfread_bytes returns all bytes read till the end of the file in ReadDataReadDataReadDataReadDatareadDataread_data and parameter IsEOFIsEOFIsEOFIsEOFisEOFis_eof is set to 1.

If no byte can be read because the end of the file is reached, ReadDataReadDataReadDataReadDatareadDataread_data is empty and IsEOFIsEOFIsEOFIsEOFisEOFis_eof is set to 1.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

FileHandleFileHandleFileHandleFileHandlefileHandlefile_handle (input_control) file → (handle)

File handle.

NumberOfBytesNumberOfBytesNumberOfBytesNumberOfBytesnumberOfBytesnumber_of_bytes (input_control) integer → (integer)

Number of bytes to be read.

ReadDataReadDataReadDataReadDatareadDataread_data (output_control) integer-array → (integer)

Bytes read from the input binary file.

IsEOFIsEOFIsEOFIsEOFisEOFis_eof (output_control) integer → (integer)

Indicates if end of file is reached while reading the file.

Example (HDevelop)

* Read a binary file 5 bytes at a time till EOF is reached.
open_file(Filename,'input_binary',FileHandle)
repeat
  fread_bytes(FileHandle, 5, BytesRead, IsEOF)
until (IsEOF)
close_file (FileHandle)

Result

If an input file is open in binary mode and no file read error occurs,the operator fread_bytesfread_bytesFreadBytesFreadBytesFreadBytesfread_bytes returns 2 (H_MSG_TRUE). Otherwise, an exception is raised.