## Duck number program in Python:

This post will show you how to check if a number is a *duck number* or not in Python. A number is called a *duck number* if the number contains at least one zero and it doesn’t start with a zero. We can also say that a positive number that has at least one zero is called a *duck number*.

For example, *12034* is a duck number because it has one zero. Similarly, *123004* is also a duck number. But *01234* is not a duck number as it starts with a zero. *012304* is a duck number because it has one zero even if we don’t consider the leading zero.

To check if a number is a *duck number* or not, we must check if the number contains a non-leading zero digit. We can write a program in different ways in Python.

### Method 1: By iterating through the digits of the number:

We can iterate through the digits of the number one by one to check if the number is a duck number. The loop will ignore the leading zeroes. Below is the complete algorithm:

- Take the number as input from the user.
- Iterate over the digits of the number one by one.
- Ignore the leading zeroes.
- If it finds any zero in the number, it will be a duck number. Else, it is
*not*a duck number.

Below is the complete program:

```
def is_duck(n):
i = 0
while i < len(n) and n[i] == '0':
i += 1
while i < len(n):
if n[i] == '0':
return True
i += 1
return False
if __name__ == '__main__':
test_number_array = ["0", "0000", "0123", "1230", "123", "1203", "120034", "012340"]
for number in test_number_array:
if is_duck(number):
print(f'{number} is a duck number')
else:
print(f'{number} is not a duck number')
```

Here,

- The
*is_duck*method is used to check if a number is a duck number or not. It takes one number as its parameter and returns one Boolean value. - The first
*while loop*is used to iterate over the leading zeroes. - The second
*while loop*iterates over other digits of the number and checks if there is any zero in the number. If it find any zero, it returns*True.*Else, if it doesn’t find any zero, it returns*False*. - The
*test_number_array*is an array of numbers. The*for loop*iterates over these numbers and checks if each number is a*duck number*or not.

It will print the below output:

```
0 is not a duck number
0000 is not a duck number
0123 is not a duck number
1230 is a duck number
123 is not a duck number
1203 is a duck number
120034 is a duck number
012340 is a duck number
```

### Method 2: By using lstrip:

The *lstrip* method is used to remove any leading character from a string in python. This method is defined as below:

`str.lstrip(characters)`

Here, *characters* are the characters we want to remove from the start of a string. This is an optional value and if we don’t pass this value, it will remove the spaces. This method returns the new string.

By using the *lstrip* method, we can remove all leading zeroes from a string and we can check if there is any zero in the remaining part of the string or not.

Below is the complete program:

```
def is_duck(n):
n_lstrip = n.lstrip("0")
if "0" in n_lstrip:
return True
return False
if __name__ == '__main__':
test_number_array = ["0", "0000", "0123", "1230", "123", "1203", "120034", "012340"]
for number in test_number_array:
if is_duck(number):
print(f'{number} is a duck number')
else:
print(f'{number} is not a duck number')
```

In this example, we changed the *is_duck* method. It uses *lstrip* to remove all leading zeroes. This value is stored in the variable *n_lstrip*. The *if* block checks if there is any zero in *n_lstrip* or not. If yes, it returns *True*. Else, it returns *False*.

It will print the below output:

```
0 is not a duck number
0000 is not a duck number
0123 is not a duck number
1230 is a duck number
123 is not a duck number
1203 is a duck number
120034 is a duck number
012340 is a duck number
```

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