How to check if a variable is string or an integer?

Question

I have a question about how to warn user to input 'string' instead of 'integer' but it seems that I cannot iterate the loop if user input is integer and ask again please enter string

Example from here

http://pythontutor.com/visualize.html#mode=edit

catNames = []

while True:

    print("Enter the name of cat " + str(len(catNames) + 1) + ' (Or enter nothing to stop):' )

    while True:

        name = input()

        try:
            name = int(name)

        except ValueError:

            print('please enter string')
            pass    

    if name == '':
        break

    catNames = catNames + [name] # list concatenation

print('The cat names are :')
for i in catNames:
    print(' ' + i)

That name will never break the outer while loop because input name is in another scope and the inner loop has nothing that breaks it, because if it gets a ValueError then it passes and runs again. — Sachihiro
– Sachihiro, Commented Mar 28, 2020 at 15:21

Sachihiro · Accepted Answer · 2020-03-28 15:25:39Z

3

A possible solution is this:

catNames = []

while True:
    print("Enter the name of cat " + str(len(catNames) + 1) + ' (Or enter nothing to stop):' )
    name = input()
    if name.isalpha():
        catNames = catNames + [name] # list concatenation
    elif name == '':
        break
    else:
        print("Please enter a string")


print('The cat names are :')
for i in catNames:
    print(' ' + i)

answered Mar 28, 2020 at 15:25

Sachihiro

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Comments

Maurice Meyer · Accepted Answer · 2020-03-28 15:26:25Z

1

One while is sufficent, in case a user enters an integer you could 'reset' the value:

catNames = []

while True:
    print("Enter the name of cat " + str(len(catNames) + 1) + ' (Or enter nothing to stop):' )
    name = input()

    if name.strip() == '':
        # no input
        print("exiting!")
        break

    try:
        name = int(name)
        name = None
        print("Please enter a string")
    except ValueError:
        pass
    finally:
        if name is not None:
            catNames.append(name)


print('The cat names are :')
for i in catNames:
    print(' ' + i)

answered Mar 28, 2020 at 15:26

Maurice Meyer

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