Check Whether Mobile Number is Valid Using Functions

Aim

Write a program to check whether the given number is a valid mobile number or not using functions in Python.

• A valid mobile number should contain exactly 10 digits.
• The first digit should be 7, 8, or 9.

Algorithm

1. Start
2. Define a function is_valid_mobile_number to check the validity of the mobile number:
   • Check if the length of the number is 10.
   • Check if the first digit is 7, 8, or 9.
   • Return True if both conditions are met, otherwise return False.
3. Take input from the user:
   • Ask the user to enter a mobile number.
4. Check the validity of the mobile number:
   • Call the is_valid_mobile_number function with the input number as an argument and store the result.
5. Print the result:
   • Display whether the mobile number is valid or not.
6. End

Program

# Define a function to check the validity of the mobile number
def is_valid_mobile_number(number):
    if len(number) == 10 and number[0] in '789':
        return True
    return False
 
# Take input from the user
mobile_number = input("Enter the mobile number: ")
 
# Check the validity of the mobile number
if is_valid_mobile_number(mobile_number):
    print(f"{mobile_number} is a valid mobile number.")
else:
    print(f"{mobile_number} is not a valid mobile number.")

Sample Input/Output

Enter the mobile number: 9876543210
9876543210 is a valid mobile number.

Enter the mobile number: 1234567890
1234567890 is not a valid mobile number.

Explanation

• We define a function is_valid_mobile_number to check the validity of the mobile number:

  • The function checks if the length of the number is 10 and if the first digit is 7, 8, or 9.
  • If both conditions are met, the function returns True, otherwise it returns False.

• We take the mobile number as input from the user and store it in the variable mobile_number.

• We check the validity of the mobile number by calling the is_valid_mobile_number function with mobile_number as an argument and store the result.

• We print the result using the statement print(f"{mobile_number} is a valid mobile number.") or print(f"{mobile_number} is not a valid mobile number.") based on the validity check.

Complexity Analysis

• The time complexity of the is_valid_mobile_number function is O(1) because it performs a constant number of operations.
• The space complexity of the is_valid_mobile_number function is O(1) because it uses a constant amount of space.

How can you improve this program?

• You can add error handling to ensure the user enters a valid number format.
• You can implement additional checks to ensure the input contains only digits.

Summary

In this tutorial, we learned how to check whether a given number is a valid mobile number or not using functions in Python. We discussed the algorithm, program, and sample input/output for validating a mobile number. We also analyzed the complexity of the validation function and suggested possible improvements.