Flow Of Execution Python
Writing Python Functions, Part 2: Flow & Scope. The Python interpreter reads a program just like you are reading this page: one line at a time, from left to right and top to bottom. The interpreter executes operations and functions in the order that it encounters them. This is called control flow or the flow of execution. code# Threading example import time, thread def myfunction(string, sleeptime, lock,.args): while True: lock.acquire time.sleep(sleeptime) lock.release time.
In Python flow is sequential as long as successive statements are indented the same amount. The for statement introduces indented sub-statements after the for-loop heading. Flow of control is often easy to visualize and understand if we draw a flowchart. This flowchart shows the exact steps and logic of how the for statement executes. I'm completely new to Python and thus a bit confused about the flow of a program in Python. If my understanding is correct, for a single.py file, if we add the line if name 'main': main. code# Threading example import time, thread def myfunction(string, sleeptime, lock,.args): while True: lock.acquire time.sleep(sleeptime) lock.release time. A program’s control flow is the order in which the program’s code executes. The control flow of a Python program is regulated by conditional statements, loops, and function calls. This section covers the if statement and for and while loops; functions are covered later in this chapter. In Python flow is sequential as long as successive statements are indented the same amount. The for statement introduces indented sub-statements after the for-loop heading. Flow of control is often easy to visualize and understand if we draw a flowchart. This flowchart shows the exact steps and logic of how the for statement executes.
Active3 years, 8 months ago
This question already has an answer here:
- What does if __name__ “__main__”: do? 29 answers
I'm completely new to Python and thus a bit confused about the flow of a program in Python.If my understanding is correct, for a single .py file, if we add the line
The interpreter finds the main function and starts executing from there.This, since Python execution goes sequentially line after line.
They work really well and come pretty quick. These computers don't have disk drives. Download acer aspire recovery disk. The instructions they come with clear up most all questions you might have.The reasoning for not using a recovery CD is very simple. Try checking the manufacture and if you cannot find the discs, order from the link above. They are a third party recovery disk company that we order from for our customers.
My question is if there are multiple .py files and 1 such file has the main function, like Java/C++ is there a way the python interpreter can know ad start executing the main function?
8433 gold badges10 silver badges32 bronze badges
marked as duplicate by Bhargav Rao♦ pythonFeb 1 '16 at 21:29
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
2 Answers
The Python interpreter knows nothing of a main() function - the flow is just line by line.
We feel we have reached this goal and helped cure more cases of nostalgia than we could have ever imagined.Thank you for all of your support throughout the years - CoolROM will continue strong. F zero gx dolphin rom. From the very beginning, our goal was to allow users to re-live classic moments from video games that they have lost and cannot purchase anymore.
The block that goes:
is a explicit call to a function if the magic variable __name__ contains the string '__main__'. That thing, the content of __name__ is the one special thing the Python runtime does when running a module: if the current module is the main program that was invoked, it contains the string __main__, otherwise its contents are rather the module name.
So, if you want your main function (which can have whatever name) placed in another file, you can just import it at invocation time:
This feature is interesting as it allows any Python file to work both as a loadable library module by other programs, and offer standalone functionality as a program.
However, for a Python package, that is, a folder containing related .py files, that each correspond to a module, Python has to choose which of these modules is run sequentially. When you execute a package using the -m directive to the Python runtime, it findes a file named __main__.py inside the package and executes that one - in the absence of such a file, the package cannot be run directly.
Follwing the same line of though, the __main__.py file is only run automatically when executing the package as the main program - if the package, or parts of it, are imported by another program, it is not executed. That, unlike checking the contents of __name__ with an if expression is actually a built-in behavior that defines a starting-place.
61.3k7 gold badges87 silver badges139 bronze badges
When you run a single Python script from the command-line with python script.py, interpretation starts at the first line and continues line by line. If a line starts a class or function definition, the definition is stored for later reference. If the line is executable code, it is directly executed. In the case of the statement if __name__ '__main__': main(), this is directly executable, if the condition evaluates to true then main() is called. However, this isn't special. You can have whatever code you wish in the if body.
52.5k16 gold badges95 silver badges186 bronze badges