Difference in read(), readline() and readlines() in Python

Question

I was looking on a web of Python the commands mentioned in title and their difference; however, I have not satisfied with a complete basic understanding of these commands.

Suppose my file has only the following content.

This is the first time I am posing a question on this site, I will appreciate if someone clarifies my doubts for learning the Python. I thank the StackOverflow for this platform.

In the commands read(), readline() and readlines(), one difference is of course reading whole file, or a single line, or specified line.

But I didn't understand the use/necessity of bracket () in these commands. For example, what is the difference in readline() and readline(7)? If the argument 7 exceeds the number of lines in the file, what will be output?

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On the web mentioned above, it is explained what the argument in read() does; but it is not mentioned what the argument in readline() or readlines() does?

Answer 1

read(n)
filevar.read()

Reads and returns a string of n characters, or the entire file as a single string if n is not provided.

readline(n)
filevar.readline()

Returns the next line of the file with all text up to and including the newline character. If n is provided as a parameter, then only n characters will be returned if the line is longer than n.

readlines(n)
filevar.readlines()

Returns a list of strings, each representing a single line of the file. If n is not provided then all lines of the file are returned. If n is provided then n characters are read but n is rounded up so that an entire line is returned.