Reads the entire file or input stream into memory.
For large files, use the ReadLine or Read methods to reduce the load on memory resources.
Files opened for writing or appending can’t be read; you
must first close the file and reopen it using the
When used to read the standard input stream from the keyboard, the ReadAll method pauses program execution and polls the keyboard until the AtEndOfStream symbol is encountered. For this reason, the ReadAll method should not be executed repeatedly in a loop.