Keep Calling a Function Until a Condition is Met - Python

In Python, we can use a loop to repeatedly call a function until a condition is met. This is useful for tasks that require continuous checking, such as waiting for a process to complete or retrying an operation until it succeeds. It ensures the function runs as long as the condition remains false.

Example:

def fun():
    p = "mypassword" # Predefined password
    s = "mypassword" # input password
    return s == p
while fun() == False:
    print("Incorrect")
print("Correct")

Correct

Explanation:

• This function checks if the entered password matches the predefined one.
• Loop prints "Incorrect" until the passwords match, then prints "Correct".

Let's take a look at other methods of calling a function with certain conditions:

Recursion

This repeatedly calls a function until the base condition is met. It is useful for problems that require repeated actions such as calculating the factorial of a number.

Example:

def fact(n):
    if n == 0 or n == 1:
        return 1
    else:
        return n * fact(n - 1)
# Input
a= 5
print(fact(a))

120

Explanation:

• This fact() function calculates the factorial of n using recursion.
• Multiplies n by fact(n-1) until n is 0 or 1.

For Loop

This is used when we know the number of iterations in advance. We can break the loop when a certain condition is met and it doesn't run indefinitely.

def fun(no):
    for i in range(2, no):
        if no % i == 0:
            print("Prime")
    print("Not Prime")
n = 7 # input
fun(n) # calling function 

Not Prime

Explanation:

• This function checks if the number is divisible by any number from 2 to no-1.