python - 跳过 Elif 条件

Question

在代码执行期间，程序会跳过所有 ELIF 条件，直接进入 ELSE，即使 ELIF 条件为 TRUE

a = 0
b = 0
c = 0
r = 0
soma = 1
sub = 2
div = 3
mult = 4
print('enter the number corresponding to the operation you want to do:\n')
print('Sum [1]')
print('Subtraction[2]')
print('Divisao [3]')
print('Multiplication [4]')
r = int(1)
while (r == 1):
    operacao = 0
    operacao = input('\n>')
    if operacao == soma:
            a = int(input('Enter the value of  a:'))
            b = int(input('Enter the value of  b:'))
            c = a + b
            print ('\n A Soma de {} mais {} equivale a: {}'.format(a,b,c))
    elif operacao == sub:
            a = int(input('Enter the value of a:'))
            b = int(input('Enter the value of b:'))
            c = a - b
            print ('\n A subtracao de {} menos {} equivale a: {}'.format(a,b,c))
    elif operacao == div:
            a = int(input('Enter the value of a:'))
            b = int(input('Enter the value of b:'))
            c = a / b
            print ('\n A divisao de {} de {} equivale a: {}'.format(a,b,c))
    elif operacao == mult:
            a = int(input('Enter the value of a:'))
            b = int(input('Enter the value of b:'))
            c = a * b
            print ('\n The multiplication of {} by {} is equivalent to: {}'.format(a,b,c))
    else: #going direct to here...
            print('\n Unrecognized operation')

预计 ELIF 条件在 true 时会起作用，但不起作用。

标签： python

Answer 1

input返回 a string，因此您需要这样做operacao = int(input('\n>'))，否则str == int将始终是False：

x = input("\n>") # I've input 5
x
# '5'

# returns False because x is a string
x == 5
# False

# converts x to int, so returns True
int(x) == 5
# True

# returns True because we are comparing to a string
x == '5'
# True

所以对于你的代码：

# convert the return of input to int for comparing against other ints
operacao = int(input('\n>')) # I'll put 3

if operacao == 1:
    print('got one')
elif operacao == 3:
    print('got three')

# got three