When you direct data into a file, it is not sent there immediately.
It is physically written to the device only when the buffer is full.
When you read data from a file, you input it from the input buffer.
When the buffer becomes empty it is refilled with a new block of data.
Why buffer?
It reduces the number of accesses to the external device.
Only cerr, standard error, is never buffered .
Errors are critical.
composed of characters
data types have to be formatted/converted into a sequence of characters
variable number of characters (bytes) for the same data types
usually sequential access
binary numbers (bits)
fixed size of the same data types
random access
more compact, less portable than text files
Text File Input/Output functions also carry out data type conversion:
Example:
int number;
outFile << number ;
The << operator converts int into a sequence of ASCII codes and writes them into a file.
int number => 145 binary format => text file stream => ASCII codes 49 52 53 => A File
inFile >> &number;
The >> operator converts a sequence of ASCII characters into an integer number and stores it into a variable.
A Binary File Stream is an interface between a program and a physical file that does not perform any type conversion .
File Streams can be Text or Binary, but physical files do not have any special marker to indicate their type.
A file name or its extension does not affect the file type
