Lower Level File I/O Functions:
Whenever reading from data file, as long as the data in the file is "regular" the load function works-in another words, the similar type of data on every line and in the similar format on every line-therefore it can be read into a matrix.
Though, data files are not always set up in this manner. Whenever it is not possible to use the load, MATLAB has what are known as lower level file input functions which can be used. The file should be opened first, that involves finding or creating the file and positioning an indicator at the starting of the file. Whenever reading has been done, the file should be closed.
Likewise, the save function can write matrices to the file, but when the output is not a simple matrix there are lower level functions to write to files. The file once again should be opened first and closed when the writing has been done.