The ReadInteger(file) command attempts to read an integer from file.   The ReadInteger command skips whitespace until an integer or non-whitespace character is found.  If there is a valid integer, it is read from file and returned.  If the characters do not form a integer, then NULL is returned.

If no integer is found, the file position is reset to its value before the call to ReadInteger was made.

To determine if the end of the file has been reached, use AtEndOfFile.

If file is the name of a file that has not been opened, Maple attempts to open the file before attempting to read the integer.

An error is raised if file is not a valid descriptor or if it is the name of a file that does not exists.