Qore Programming Language Reference Manual 1.19.2
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Qore::FileInputStream Class Reference

This class implements the InputStream interface for reading bytes from a file. More...

#include <QC_FileInputStream.dox.h>

Inheritance diagram for Qore::FileInputStream:
[legend]

Public Member Methods

 constructor (string fileName, timeout timeout_ms=-1, *bool nonblocking_open)
 Creates the FileInputStream by opening a file. More...
 
int peek ()
 Peeks the next byte available from the input stream; returns -1 if no more data available. More...
 
*binary read (int limit)
 Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream. More...
 
- Public Member Methods inherited from Qore::InputStream
 constructor ()
 Constructor. More...
 
abstract int peek ()
 Peeks the next byte available from the input stream; returns -1 if no more data available. More...
 
abstract *binary read (int limit)
 Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream. More...
 
- Public Member Methods inherited from Qore::StreamBase
 constructor ()
 Throws an exception if called directly; this class can only be instantiated by builtin subclasses. More...
 
int getThreadId ()
 Get the currently assigned thread id or -1 if not assigned to any thread.
 
nothing reassignThread ()
 Reassigns current thread as thread used for stream manipulation. More...
 
nothing unassignThread ()
 Unassigns current thread as thread used for stream manipulation. More...
 

Detailed Description

This class implements the InputStream interface for reading bytes from a file.

Restrictions:
Qore::PO_NO_FILESYSTEM
Example: FileInputStream basic usage
FileInputStream fis("file.ext");
binary *b;
while (b = fis.read(100)) {
printf("read %s\n", make_hex_string(b));
}
Note
stream classes are not designed to be accessed from multiple threads; they have been implemented without locking for fast and efficient use when used from a single thread. For methods that would be unsafe to use in another thread, any use of such methods in threads other than the thread where the constructor was called will cause a STREAM-THREAD-ERROR to be thrown, unless the stream is handed off to another thread using the StreamBase::unassignThread() method in the thread that currently owns the stream, and the StreamBase::reassignThread() method in the new thread.
See also
StreamReader for a class that can be used to read various kinds of data from an InputStream
Since
Qore 0.8.13

Member Function Documentation

◆ constructor()

Qore::FileInputStream::constructor ( string  fileName,
timeout  timeout_ms = -1,
*bool  nonblocking_open 
)

Creates the FileInputStream by opening a file.

Parameters
fileNamethe name of the file to open
timeout_msa timeout period with a resolution of milliseconds (a relative date/time value; integer arguments will be assumed to be milliseconds); if not given or negative the operations will never time out
nonblocking_openif True, then the O_NONBLOCK flag will be set in the call to open() (2)
Exceptions
FILE-OPEN2-ERRORif the file cannot be opened (does not exist, permission error, etc)
Since
Qore 0.9.3 added the nonblocking_open flag

◆ peek()

int Qore::FileInputStream::peek ( )
virtual

Peeks the next byte available from the input stream; returns -1 if no more data available.

Returns
the next byte available from the input stream or -1 if no more data is available
Example:
FileInputStream fis("file.ext");
int nextByte = fis.peek();
Exceptions
FILE-READ-ERRORif an I/O error occurs
FILE-READ-TIMEOUT-ERRORif no byte could be read in the timeout specified in the constructor
STREAM-THREAD-ERRORthis exception is thrown if this method is called from any thread other than the thread that created the object

Implements Qore::InputStream.

◆ read()

*binary Qore::FileInputStream::read ( int  limit)
virtual

Reads bytes (up to a specified limit) from the input stream; returns NOTHING if there are no more bytes in the stream.

Parameters
limitthe maximum number of bytes to read
Returns
the read bytes (the length is between 1 and `limit` inclusive) or NOTHING if no more bytes are available
Example:
FileInputStream fis("file.ext");
*binary b;
while (b = fis.read(2)) {
printf("read %s\n", make_hex_string(b));
}
Exceptions
FILE-READ-ERRORif an I/O error occurs
FILE-READ-TIMEOUT-ERRORif no byte could be read in the timeout specified in the constructor
INPUT-STREAM-ERRORlimit is not positive
STREAM-THREAD-ERRORthis exception is thrown if this method is called from any thread other than the thread that created the object
See also
FileInputStream::readString()

Implements Qore::InputStream.