擅长:python、mysql、java
<p>这就是我相信你在寻找的逻辑。在</p>
<p>如果卡片长度是16,它会检查第一个字符以确定哪种类型。在</p>
<pre><code>CreditCardNum = input("Input a credit card number(no spaces/hyphens): ")
n = len(CreditCardNum)
if n != 16:
print("This is not a valid number, make sure the number is 16 characters.")
else:
x = CreditCardNum[0]
if x == '4':
print("The Card is a Visa")
elif x == '5':
print("The Card is a Master Card")
elif x == '6':
print("The Card is a Discover Card.")
else:
print("The brand could not be determined.")
</code></pre>
<p><strong>说明</strong></p>
<ul>
<li>使用<code>n = len(CreditCardNum)</code>在变量<code>n</code>中存储输入字符串中的字符数。同样,输入的第一个字符。在</li>
<li><code>len(16)</code>没有逻辑意义。您要将<code>n</code>与另一个整数进行比较。在</li>
<li>要提取字符串的第一个字母,只需执行<code>mystr[0]</code>。在</li>
</ul>