Computer Science · Ch 7 — Functions

Summary

Functions are used in programming to achieve modularity and reusability.
A function is a named group of instructions that executes when the function is invoked (called) by its name. Functions written by the programmer are user defined functions.
The Python interpreter has many functions permanently built into it — the frequently used built-in functions such as input(), int() and print().
An argument is a value passed to a function during the function call; it is received in a parameter defined in the function header.
Python allows a parameter to be given a default value, used when the call supplies no corresponding argument.
A function sends value(s) back to its caller using the return statement.
Multiple values are returned from a Python function packed in a tuple.
Flow of execution is the order in which the statements of a program are executed; a function's body runs only when the function is called, and control returns to the point of the call afterwards.
The scope of a variable is the part of the program where the variable is accessible.
A global variable is defined outside any function or block and can be accessed anywhere in the program.
A local variable is defined inside a function or block, is accessible only there, and exists only while the function executes.
The Python standard library is an extensive collection of functions and modules that speeds up program development. …