问题
I just wrote a simple calculator script in python, generally python should recognize the (-)minus,(*)multiplication,(/)divide sign by default but while considering this script it's fails to identify the signs. please leave your comments to clear me...
#! /usr/bin/python
print("1: ADDITION")
print("2: SUBTRACTION")
print("3: MULTIPLICATION")
print("4: DIVISION")
CHOICE = raw_input("Enter the Numbers:")
if CHOICE == "1":
a = raw_input("Enter the value of a:")
b = raw_input("Enter the value of b:")
c = a + b
print c
elif CHOICE == "2":
a = raw_input("Enter the value of a:")
b = raw_input("Enter the value of b:")
c = a - b
print c
elif CHOICE == "3":
a = raw_input("Enter the value of a:")
b = raw_input("Enter the value of b:")
c = a * b
print c
elif CHOICE == "4":
a = raw_input("Enter the value of a:")
b = raw_input("Enter the value of b:")
c = a / b
print c
else:
print "Invalid Number"
print "\n"
回答1:
You need to change your inputs, strings to integer or float. Since, there is division you are better change it to float.
a=int(raw_input("Enter the value of a:"))
a=float(raw_input("Enter the value of a:"))
回答2:
When you get the input it is a string. The + operator is defined for strings, which is why it works but the others don't. I suggest using a helper function to safely get an integer (if you are doing integer arithmetic).
def get_int(prompt):
while True:
try:
return int(raw_input(prompt))
except ValueError, e:
print "Invalid input"
a = get_int("Enter the value of a: ")
回答3:
Billwild said u should change to make your variables integers. But why not float. It is not important if it is integer or float it must be number type. Raw_input takes any input like string.
a=float(raw_input('Enter the value of a: '))
Or for Tim's aproach
def get_float(prompt):
while True:
try:
return float(raw_input(prompt))
except ValueError, e:
print "Invalid input"
a = get_float("Enter the value of a: ")
You can always convert result to float or to int or back. It is just matter what kind of calculator u are programming.
来源：https://stackoverflow.com/questions/13509078/basic-calculator-program-in-python