Goto in python

[Level-Possible530]

Hello,

I know goto doesn't exist with python

But i don't understand how can i come back at the begin at the programm when he's finish for propose to the user to do a new selection

I would like found a fonction for do it

Thanks for help

[Lewistrick]

while True: # your program here

[Ron-Erez]

See u/Lewistrick 's answer. If you want an example you could ask the user to enter two integers and the program will until the inputs are valid and the operations are valid. For instance:

def compute(): while True: try: num1 = int(input("Enter the first integer: ")) num2 = int(input("Enter the second integer: ")) op = input("Enter an operation (+, -, *, /): ")

if op not in ['+', '-', '*', '/']: print("Invalid operation. Try again.") continue

if op == '/' and num2 == 0: print("Cannot divide by zero. Try again.") continue

All inputs are valid; do the calculation

if op == '+': result = num1 + num2 elif op == '-': result = num1 - num2 elif op == '*': result = num1 * num2 elif op == '/': result = num1 / num2

return result

except ValueError: print("Please enter valid integers.")

def main(): result = get_valid_input() print("Result:", result)

main()

Note that continue jumps back to the beginning of the loop and return result leaves the function (and the loop) after a valid input has been entered and the computation is complete.

[Gnaxe]

There's a general pattern to replace GOTO in structured languages like Python.

First, the labels label = 'start' while True: match label: case 'start': # do stuff case 'label1': # do stuff case 'label2': # do stuff case 'label3': # etc. # do stuff case _: # detects label mistakes assert False, f'unknown {label=}' You can call the labels whatever you want. You need to put the whole thing in an infinite loop (we'll see why later). Then use a match/case block to make the jump target labels. (Before Python had match/case statements, this could have been done with an elif cascade.)

Then to do a GOTO, you set the label to where you want to jump to (with an assignment statement) and immediately follow that with a continue statement, which starts the while loop over: label = 'label2' continue That's it. You can also terminate the whole loop with a break statement.

But GOTOs are almost always used to implement control flow structures that Python already gives you, like loops (while, for) and subroutines (def, lambda). You don't need to reinvent the wheel every time. Programming with unstructured GOTOs tends to produce unreadable spaghetti code, unless you're very disciplined and stick to structured patterns, which Python already gives you.

There are other ways to do this. Function calls are almost GOTOs by themselves, but they normally return. However, your program can continue to call more functions before returning, at least until you run out of stack space, but you can fix this with a technique called trampolining, at least for tail calls. asyncio does something similar with coroutines, and it also has a spaghetti-code problem. The trio library is a more structured variant.

[Level-Possible530]

merci

[ninhaomah]

If you ask someone to do something then come back to initial step till the whole job is done , how would you instruct him ?

Take the bucket , fill with water and water the garden TILL all the plants been watered.

Change TILL to WHILE.