Python循環從列表中返回一個值

Question

我在理解它的工作原理時遇到了一些問題。 假設我有一個學生名單，他們的 ID、姓名和成績如下，我想做一個程序，讓你輸入學生的 ID 並打印出平均成績：

students = [ #list of id, name and grades
    ("123", "Adam", [58, 68, 74]), \
    ("925", "Bob", []), \
    ("456", "Carly", [68, 72, 100]), \
    ("888", "Deborah", [68, 99, 100]), \
    ("789", "Ethan", [52, 88, 73])
]
input_id = str(input("Enter Student id: "))
student_num = 0
while student_num < len(students):
  student = students[student_num]
  student_id = student[0]
  student_name = student[1]
  student_grades = student[2]
  if input_id == student_id:
    print(student_name, sum(student_grades)/len(student_grades))
  elif student_grades == []:
    print(student_name, "has no grades")
  else: print(input_id, "not found")
  student_num += 1

這輸出這個結果

> Enter Student id: 456
> 456 not found
> Bob has no grades
> Carly 80.0
> 456 not found
> 456 not found

我如何讓它只打印卡莉？ 提前致謝！

Answer 1

只需刪除其他打印，也是一個 for 循環和解包將使代碼更易於閱讀

input_id = input("Enter Student id: ")
for student_id, student_name, student_grades in students:
    if input_id == student_id:
        print(student_name, sum(student_grades) / len(student_grades))

Enter Student id: 456
Carly 80.0

Answer 2

你的代碼需要一些重組和一些額外的邏輯

students = [ #list of id, name and grades
    ("123", "Adam", [58, 68, 74]), \
    ("925", "Bob", []), \
    ("456", "Carly", [68, 72, 100]), \
    ("888", "Deborah", [68, 99, 100]), \
    ("789", "Ethan", [52, 88, 73])
]
input_id = str(input("Enter Student id: "))
student_num = 0
found = False
while student_num < len(students):
    student = students[student_num]
    student_id = student[0]
    if input_id == student_id:
        found = True
        student_name = student[1]
        student_grades = student[2]
        if student_grades == []:
            print(student_name, "has no grades")
            
        else:
            print(student_name, sum(student_grades)/len(student_grades))
            
    
    student_num += 1
if found == False:
    print(input_id, "not found")