Comment puis-je convertir une chaîne en un int en Python?

La sortie que je reçois pour mon petit exemple d'application est la suivante:

Welcome to the Calculator!
Please choose what you'd like to do:
0: Addition
1: Subtraction
2: Multiplication
3: Division
4: Quit Application
0
Enter your first number: 1
Enter your second number: 1
Your result is:
11

C'est parce que l'addition() la méthode est la prise de l'entrée() comme des chaînes de caractères et non des nombres. Comment puis-je les utiliser comme des nombres?

Voici mon script:

def addition(a, b):
    return a + b

def subtraction(a, b):
    return a - b

def multiplication(a, b):
    return a * b

def division(a, b):
    return a / b

keepProgramRunning = True

print "Welcome to the Calculator!"

while keepProgramRunning:    
    print "Please choose what you'd like to do:"

    print "0: Addition"
    print "1: Subtraction"
    print "2: Multiplication"
    print "3: Division"
    print "4: Quit Application"



    #Capture the menu choice.
    choice = raw_input()    

    if choice == "0":
        numberA = raw_input("Enter your first number: ")
        numberB = raw_input("Enter your second number: ")
        print "Your result is:"
        print addition(numberA, numberB)
    elif choice == "1":
        numberA = raw_input("Enter your first number: ")
        numberB = raw_input("Enter your second number: ")
        print "Your result is:"
        print subtraction(numberA, numberB)
    elif choice == "2":
        numberA = raw_input("Enter your first number: ")
        numberB = raw_input("Enter your second number: ")
        print "Your result is:"
        print multiplication(numberA, numberB)
    elif choice == "3":
        numberA = raw_input("Enter your first number: ")
        numberB = raw_input("Enter your second number: ")
        print "Your result is:"
        print division(numberA, numberB)
    elif choice == "4":
        print "Bye!"
        keepProgramRunning = False
    else:
        print "Please choose a valid option."
        print "\n"

source d'informationauteur

15

Puisque vous êtes en train de rédiger un calculateur qui serait sans doute aussi accepter de flotteurs (1.5, 0.03), d'une façon plus robuste serait d'utiliser cette simple fonction d'assistance:
```
def convertStr(s):
    """Convert string to either int or float."""
    try:
        ret = int(s)
    except ValueError:
        #Try float.
        ret = float(s)
    return ret
```
De cette façon, si l'int de conversion ne fonctionne pas, vous aurez un flotteur retourné.

Edit: Votre division fonction pourrait aussi entraîner certains visages tristes, si vous n'êtes pas pleinement conscient de comment python 2.x poignées de division entière.

En bref, si vous voulez 10/2 à l'égalité des 2.5 et pas 2vous aurez besoin de faire from __future__ import division ou en fonte de l'une ou des deux arguments de flotter, comme suit:
```
def division(a, b):
    return float(a) / float(b)
```

>>> a = "123"
>>> int(a)
123

Voici quelques freebie code:

def getTwoNumbers():
    numberA = raw_input("Enter your first number: ")
    numberB = raw_input("Enter your second number: ")
    return int(numberA), int(numberB)

Peut-être le suivant, puis votre calculatrice peut utiliser nombre arbitraire de base (par exemple, hexadécimal, binaire, base de 7! etc): (non testé)

def convert(str):
    try:
        base = 10  # default
        if ':' in str:
            sstr = str.split(':')
            base, str = int(sstr[0]), sstr[1]
        val = int(str, base)
    except ValueError:
        val = None

    return val

val = convert(raw_input("Enter value:"))
# 10     : Decimal
# 16:a   : Hex, 10
# 2:1010 : Binary, 10

facile!

    if option == str(1):
        numberA = int(raw_input("enter first number. "))
        numberB= int(raw_input("enter second number. "))
        print " "
        print addition(numberA, numberB)
     etc etc etc

def plus(a, b):
de retour a + b

def soustraction(a, b):
de retour a - b

def de multiplication(a, b):
de retour a * b

def division(a, b):
de retour a /b

keepProgramRunning = True

print "Bienvenue dans la Calculatrice!"

tout keepProgramRunning:

print "Veuillez choisir ce que vous voulez faire:"

print "0: Addition"
print "1: Subtraction"
print "2: Multiplication"
print "3: Division"
print "4: Quit Application"



#Capture the menu choice.
choice = raw_input()    

if choice == "0":
    numberA = input("Enter your first number: ")
    numberB = input("Enter your second number: ")
    print "Your result is: " + str(addition(numberA, numberB)) + "\n"
elif choice == "1":
    numberA = input("Enter your first number: ")
    numberB = input("Enter your second number: ")
    print "Your result is: " + str(subtraction(numberA, numberB)) + "\n"
elif choice == "2":
    numberA = input("Enter your first number: ")
    numberB = input("Enter your second number: ")
    print "Your result is: " + str(multiplication(numberA, numberB)) + "\n"
elif choice == "3":
    numberA = input("Enter your first number: ")
    numberB = input("Enter your second number: ")
    print "Your result is: " + str(division(numberA, numberB)) + "\n"
elif choice == "4":
    print "Bye!"
    keepProgramRunning = False
else:
    print "Please choose a valid option."
    print "\n"

Tout en appelant votre sous-fonctions de vos principales fonctions vous pouvez convertir les variables de type int, et ensuite appeler. Veuillez consulter le code ci-dessous:

import sys
print("Welcome to Calculator\n")
print("Please find the options:\n" + "1. Addition\n" + "2. Subtraction\n" + 
"3. Multiplication\n" + "4. Division\n" + "5. Exponential\n" + "6. Quit\n")
def calculator():
choice = input("Enter choice\n")
if int(choice) == 1:
a = input("Enter first number\n")
b = input("Enter second number\n")
add(int(a), int(b))
if int(choice) == 2:
a = input("Enter first number\n")
b = input("Enter second number\n")
diff(int(a), int(b))
if int(choice) == 3:
a = input("Enter first number\n")
b = input("Enter second number\n")
mult(int(a), int(b))
if int(choice) == 4:
a = input("Enter first number\n")
b = input("Enter second number\n")
div(float(a), float(b))
if int(choice) == 5:
a = input("Enter the base number\n")
b = input("Enter the exponential\n")
exp(int(a), int(b))
if int(choice) == 6:
print("Bye")
sys.exit(0)
def add(a, b):
c = a+b
print("Sum of {} and {} is {}".format(a, b, c))
def diff(a,b):
c = a-b
print("Difference between {} and {} is {}".format(a, b, c))
def mult(a, b):
c = a*b
print("The Product of {} and {} is {}".format(a, b, c))
def div(a, b):
c = a/b
print("The Quotient of {} and {} is {}".format(a, b, c))
def exp(a, b):
c = a**b
print("The result of {} to the power of {} is {}".format(a, b, c))
calculator()

Ici ce que j'ai fait est que j'ai appelé chacun de la fonction lors de la conversion des paramètres d'entrée à l'int. J'espère que cela a été utile.

Dans votre cas, il pourrait être modifié comme ceci:

 if choice == "0":
numberA = raw_input("Enter your first number: ")
numberB = raw_input("Enter your second number: ")
print "Your result is:"
print addition(int(numberA), int(numberB))

-1

def addition(a, b): return a + b
def subtraction(a, b): return a - b
def multiplication(a, b): return a * b
def division(a, b): return a / b
keepProgramRunning = True
print "Welcome to the Calculator!"
while keepProgramRunning:
print "Please choose what you'd like to do:"

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