如何檢查號碼是否與列表中的號碼相同

Question

我想檢查用戶輸入的數字是否與列表中的數字相同，以及我 select 列表中的項目使用 for 循環與數字進行比較的方式不起作用。 就像它只是遍歷列表中的第一項。 即使我輸入 43（示例），它仍然會打印（列表中有 43），我認為第一項是 65，這與 43 不同。

ARR = [65,75,85,95,105]

def check_number ():
    NUM = int (input ("Please enter the number you want to check with"))
    for x in range (len (arr)):   
        check == ARR [x]
    if check == ARR [x]:
        print (NUM,"is available in the list")      
    else:
        print (NUM,"is not available is the list")
check_number ()

Answer 1

檢查一個值（包括數字和字符串的任何可散列值）是否是列表成員的更好方法是使用 Python 的內置set類型：

arr = set([65, 75, 85, 95, 105])

def check_number():
    num = int (input ("Please enter the number you want to check with"))
    if num in arr:
        print (num, "is available in the list")      
    else:
        print (num, "is not available is the list")

check_number ()

對於更大的數據集，它既更省時，也更慣用。

Answer 2

你可以簡單地做

ARR = [65,75,85,95,105]

def check_number ():
    NUM = int (input ("Please enter the number you want to check with"))

    if NUM in ARR:
        print (NUM,"is available in the list")      
    else:
        print (NUM,"is not available is the list")
check_number ()

使用in檢查數組是否包含元素是“ pythonic ”的方法。

Answer 3

您可以使用in關鍵字進行比較。

ARR = [65,75,85,95,105]

def check_number ():
    NUM = int (input ("Please enter the number you want to check with"))
    if NUM in ARR:
        print(NUM, ' is available in this list')
    else:
        print(NUM, ' is not available in this list')
check_number()

Answer 4

無需使用loop進行比較，因為它會traverse並將number與list進行比較。 這是一個有點冗長的過程，而不是你可以使用in來比較number和list 。 相同場景的代碼如下所述：-

# Declared List named 'ARR'
ARR = [65,75,85,95,105]

# Declaration of 'check_number()' function for checking whether Number is Present in list or not
def check_number ():

    # User imput of 'Number' for Comparision
    NUM = int (input ("Please enter the number you want to check with:- "))

    # If 'Number (NUM)' is present in 'List (ARR)'
    if NUM in ARR:
        print (NUM, "is available in the list") 

    # If 'Number (NUM)' is not present in 'List (ARR)'
    else:
        print (NUM, "is not available is the list")

check_number()

# Output_1 for the above code is given below:-
Please enter the number you want to check with:- 45
45 is not available is the list

# Output_2 for the above code is given below:-
Please enter the number you want to check with:- 65
65 is available in the list