SyntaxError 语法无效 python

Question

def convert():
    choice = input("Wybierz kierunek wymiany waluty \n1) PLN>USD \n2) USD>PLN \n3) PLN>EURO \n4) EURO>PLN")
    print(choice)

    if choice == 1:
        print ("choice=1")

    else choice == 2:
        print("Choice=2")

    else choice == 3:
        print("Choice=3")

    else choice == 4:
        print("Choice=4")

convert()

Why is there a SyntaxError: invalid syntax ?

Answer 1

You probably meant elif - there is no else <cond> in python:

def convert():
    choice = input("Wybierz kierunek wymiany waluty \n1) PLN>USD \n2) USD>PLN \n3) PLN>EURO \n4) EURO>PLN")
    print(choice)
    if choice == "1":
        print("choice=1")
    elif choice == "2":
        print("Choice=2")
    elif choice == "3":
        print("Choice=3")
    elif choice == "4":
        print("Choice=4")

convert()

See the docs for how to use if-elif-else.

Answer 2

There is this trio in python: if , elif , and else . There can only be one else , because, just think of what it actually means: only do something when all other conditions don't pass.

def convert():
    choice = input("Wybierz kierunek wymiany waluty \n1) PLN>USD \n2) USD>PLN \n3) PLN>EURO \n4) EURO>PLN")
    print(choice)

    if choice == 1:
        print ("choice=1")

    elif choice == 2:
        print("Choice=2")

    elif choice == 3:
        print("Choice=3")

    elif choice == 4:
        print("Choice=4")

convert()

Answer 3

While traditional way to fix your code is by replacing all else except the last one with elif as follows:

def convert():
    choice = input("Wybierz kierunek wymiany waluty \n1) PLN>USD \n2) USD>PLN \n3) PLN>EURO \n4) EURO>PLN")
    print(choice)
    if choice == "1":
        print("choice=1")
    elif choice == "2":
        print("Choice=2")
    elif choice == "3":
        print("Choice=3")
    elif choice == "4":
        print("Choice=4")

convert()

However for your particular case, even if else isn't needed. You can go for:

def convert():
        choice = input("Wybierz kierunek wymiany waluty \n1) PLN>USD \n2) USD>PLN \n3) PLN>EURO \n4) EURO>PLN")
        print(choice)
        print("choice=", choice)

convert()