Assert related question

Question

How can I be sure that an user input is an integer, not a letter?

Answer 1

You can test the input (let's call it inp) if it consists only of digits.

inp.isdigit()

It returns either True or False.

Answer 2

# Using try/except/else (recommended)
a = input()
try:
int(a)
except ValueError:
# your code
print('Not an integer!')
else:
# your code
print('Integer')

# Using assert
a = input()
assert a.isdigit(), 'Not a digit!'

Answer 3

You should not use assert for this, because it's only a debugging tool.

Depending on how the program is run, assert statements may be ignored by the interpreter.

Bad, if your code relies on them!

Answer 4

Agree with HonFu.
Use try/else statements to handle errors

Answer 5

Thanks Asman-H and HonFu for your answers, they were very clarifying.

As I didn't know there is a method for this, I was writing something like

eggs = input("Enter an integer:\n")
assert eggs < "a", "Not an integer"

But your versions are far more advantageous.