Question

如果值不存在，我想设置一个条件，然后执行一些顺序操作，如果值不存在，则执行其他操作

def func():
    first_array = [1, 3, 5, 7, 9]
    second_array = [2, 4, 6, 8, 10]
    found = False

    for i in range(len(first_array)):
        if first_array[i] == second_array[i]:
            found = True
            indeks_found = i
        if found == True:
            break

局部变量 indeks_found 不存在（或 indeks_found 没有任何值）。 [我不知道]

其他情况，如果我们把数组改成这样：

first_array = [1, 3, 5, 7, 9]
second_array = [2, 4, 5, 11, 13]

那么，indeks_found 是存在的（或者 indeks_found 确实有值）[我不知道]

如果 indeks_found 有任何值，则执行此顺序操作（我们称之为 A）否则如果 indeks_found 没有任何值，则执行此顺序操作（我们称之为 B）

if indeks_found exist, then:
    do A
else: indeks_found doesn't exist, then:
    do B

那么，如何在python中制作这个源代码？

Answer 1

def func():
    first_array = [1, 3, 5, 7, 9]
    second_array = [2, 4, 6, 8, 10]
    found = False
    indeks_found = None # initialize to none

    for i in range(len(first_array)):
        if first_array[i] == second_array[i]:
            found = True
            indeks_found = i
        if found == True:
            break
    if indeks_found == None:
        # indeks_found was not changed, i.e nothing found
        print('do A')
    else:
        print('do B')

您也可以将 for 循环体简化为：

        if first_array[i] == second_array[i]:
            found = True
            indeks_found = i
            break

如果你真的想测试一个变量是否已经定义，你可以这样做：

try:
    indeks_found
except NameError:
    # indeks_found was not defined
else:
    # indeks_found has a value

如果值不存在，则如何设置条件，然后执行一些顺序操作，如果值不存在，则执行其他操作

1 个答案: