即使条件为假，“While”循环仍在无限运行

Question

There is a while loop in line 14. Even if I enter M or F, it still gives the input. It doesn't continue.

import array

# Declaration of variables
Constnostudents = int(3)
StudentName = []
StudentGender = []

# Declaration of arrays
StudentMarkTest1 = array.array ("i", range(Constnostudents))
StudentMarktest2 = array.array ("i", range(Constnostudents))

for Counter in range(0, Constnostudents):
    StudentName.append (input("Please enter name of student"))
    StudentGender.append (input("Please enter your gender"))
    while (StudentName[Counter] !="M" or StudentName[Counter] != "F"):
        input("Please enter valid ")

    StudentMarkTest1[Counter] = int(input("Please enter marks for test 1"))
    StudentMarktest2[Counter] = int(input("Please enter marks for test 2"))

print(StudentName)
print(StudentGender)
print(StudentMarkTest1)
print(StudentMarktest2)

Answer 1

If you are trying to check if the gender they provided is a valid one, you are giving the wrong value to the while loop. You need to give the "StudentGender" variable and not the "StudentName" variable. Also you are not reassigning the " StudentGender", so it doesn't matter if they are going to provide a valid answer. The loop will continue to run...

You should do:

while (StudentGender[Counter] !="M" and StudentGender[Counter] != "F"):
       StudentGender[Counter] = input("Please enter valid gender").upper()

I also added .upper() to the gender.

For the reason of the "and" instead of "or", look at the comments in your question.