CODEWITHSUNDEEP
c
Van Teo Le
Van Teo Le

Reputation: 156

Relationship between stream and buffer?

I'm a newbie programmer, can you help me imagine what a stream is, is it a fixed array of bytes that transfer data from i.e: a file to Y? And what is Y here, a buffer or something else? In what way is the buffer related to stream?

Upvotes: 0

Views: 764

Answers (2)

sahushivam
sahushivam

Reputation: 109

Difference between a buffer and a stream is

A Stream is a sequence of bytes of data that transfers information from or to a specified source.

A sequence of bytes flowing into a program is called input stream. A sequence of bytes flowing out of the program is called output stream Use of Stream makes I/O machine independent.

A Buffer is a sequence of bytes that are stored in memory.

In C, I/O operations are asynchronous: you don’t know when you have data nor how much of it. So a buffer is usually used to collect data from the stream (file, socket, device). When the buffer is full, consumers of that stream are notified and can consume data from the buffer until is depleted. Then wait for the buffer to be filled again before using that data. It is a place to store something temporarily, in order to mitigate differences between the input speed and output speed. While the producer is being faster than the consumer, the producer can continue to store the output in the buffer. When the consumer speeds up, it can read from the buffer. The buffer is there in the middle to bridge the gap.

Y in your question can be a file, socket or a device(I/O).

Hope this solves your Query :)

Upvotes: 1

Amadan
Amadan

Reputation: 198324

A stream is either a source (input stream) or sink (output stream) of data, that is available (or provided) in time (as opposed to all at once).

A buffer is an array (a piece of memory) that is used to store data temporarily. An input buffer is typically filled from an input stream by the OS; an output buffer (once filled by the programmer) is consumed by the OS.

Imagine you want to fill a tub with water. You start with a water source like a water tank or public waterworks that can be transfered through a water tap. You put a bucket under the water tap and turn it on. When the bucket is full, you dump it into the tub, and put it back under the tap. You repeat that until your tub is full.

Loading a file, for example, works almost the same way. You have a data source (the file on disk); you open an input stream (a programmatic construct that will give you data generally as fast as the disk can read them). You allocate a buffer (a small memory area) and tell the system to fill it from the stream. When it is full, you append it to the big chunk of allocated memory that you reserved for file contents, then let the buffer be filled again. When the whole file is read, you close the stream.

Upvotes: 3

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