web-dev-qa-db-fra.com

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

Le résultat obtenu pour mon petit exemple d'application est le suivant:

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

En effet, la méthode addition () considère que input () est une chaîne et non un nombre. Comment puis-je les utiliser comme nombres?

Voici mon script entier:

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"
pythonstringint
10
delete

Puisque vous écrivez une calculatrice qui accepterait vraisemblablement les flottants (1.5, 0.03), une méthode plus robuste consisterait à utiliser cette fonction d’aide simple:

def convertStr(s):
    """Convert string to either int or float."""
    try:
        ret = int(s)
    except ValueError:
        #Try float.
        ret = float(s)
    return ret

Ainsi, si la conversion int ne fonctionne pas, un float est renvoyé.

Edit: Votre fonction division peut également donner des visages tristes si vous n’êtes pas pleinement conscient de comment python 2.x gère la division entière . 

En bref, si vous voulez que 10/2 soit égal à 2.5 et pas2, vous devrez faire from __future__ import division ou transtyper un des arguments ou les deux pour flotter, comme suit: 

def division(a, b):
    return float(a) / float(b)
15
Aphex
>>> a = "123"
>>> int(a)
123

Voici un code de billet de faveur:

def getTwoNumbers():
    numberA = raw_input("Enter your first number: ")
    numberB = raw_input("Enter your second number: ")
    return int(numberA), int(numberB)
11
hughdbrown

Peut-être que votre calculatrice peut utiliser la base de nombre arbitraire (par exemple, hexadécimal, binaire, base 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
0
Nick

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
0
Richard

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

def soustraction (a, b): retourne a - b

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

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

keepProgramRunning = True

print "Bienvenue dans la calculatrice!"

pendant que keepProgramRunning:
print "S'il vous plaît choisissez ce que vous souhaitez 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"
0
Munst

Lorsque vous appelez vos sous-fonctions à partir de vos fonctions principales, vous pouvez convertir les variables en int, puis appeler. Veuillez vous référer au 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()

Voici ce que j’ai fait: j’ai appelé chacune des fonctions lors de la conversion des paramètres entrés en int. J'espère que cela a été utile.

Dans votre cas, cela pourrait être changé 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))
0
Chippy