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Question

我写了一个简单的程序来检查字符串是否是彼此的子串。问题是我不断得到列表索引超出界限错误。

我尝试在每次迭代时打印i和j，它们永远不会超出列表的范围。我甚至试图在s [5]和s [6]插入元素来检查索引，但仍然得到相同的错误。可能是造成此错误的原因是什么？

s = []                                        
s.insert(0,str("a b c"))
s.insert(1,str("a b c d"))
s.insert(2,str("a b"))
s.insert(3,str("b c"))
s.insert(4,str("d"))

j = 0
i = 0

while j < 5:
    if s[j] in s[i]:
        print("\"" + s[j] + "\" is in the string \"" + s[i] + "\"")
    i +=1
    if i == 5 and j < 4:
        j+=1
        i=0

这是我的控制台输出

Traceback (most recent call last):
"a b c" is in the string "a b c"
  File "C:/Users/Kal/PycharmProjects/untitled/FSS2.py", line 16, in <module>
"a b c" is in the string "a b c d"
    if s[j] in s[i]:
"a b c d" is in the string "a b c d"
IndexError: list index out of range
"a b" is in the string "a b c"
"a b" is in the string "a b c d"
"a b" is in the string "a b"
"b c" is in the string "a b c"
"b c" is in the string "a b c d"
"b c" is in the string "b c"
"d" is in the string "a b c d"
"d" is in the string "d"

Process finished with exit code 1

Answer 1

问题出在第18行

s = []                                        
s.insert(0,str("a b c"))
s.insert(1,str("a b c d"))
s.insert(2,str("a b"))
s.insert(3,str("b c"))
s.insert(4,str("d"))
print(s)
j = 0
i = 0

while j < 5:
    if s[j] in s[i]:

        print("\"" + s[j] + "\" is in the string \"" + s[i] + "\"")
    i +=1
    if i == 5 and j < 4: <-- here
        j+=1
        i=0

在某些时候，您的i = 5和j = 4，因此此if i == 5 and j < 4语句的右侧为False，而i未重置为0.所以在下一个循环中，i等于5，最大索引为4.

更好的解决方案是使用for循环。

s = []                                        
s.insert(0,str("a b c"))
s.insert(1,str("a b c d"))
s.insert(2,str("a b"))
s.insert(3,str("b c"))
s.insert(4,str("d"))
for i in range(len(s)):
   for j in range(len(s)):
       if s[i] in s[j]:
          print("\"" + s[i] + "\" is in the string \"" + s[j] + "\"")

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s = []                                        
s.insert(0,str("a b c"))
s.insert(1,str("a b c d"))
s.insert(2,str("a b"))
s.insert(3,str("b c"))
s.insert(4,str("d"))
j = 0
i = 0

while j < len(s):
    if s[j] in s[i]:
        print("\"" + s[j] + "\" is in the string \"" + s[i] + "\"")
    i +=1
    if i == len(s):
       j+=1
       i=0

Answer 2

只有当i已经为5时，你才会增加j（注意if子句中的and）。因此，当i = 5时，你仍处于while循环中（仅取决于j）并且你试图访问未定义的s [i] = s [5]。

Answer 3

当您的代码引发异常时，i的值为5，j的值为4.在print语句中，您尝试要做s[i]即s[5]，并且由于s的最大索引为4，因此您的代码正在提升IndexError。

我相信，在您的代码中，您需要在if语句中进行修改：

if i == 5 and j < 5:  # Instead of j < 4

然后你的代码运行良好：

>>> while j < 5:
...     if s[j] in s[i]:
...         print("\"" + s[j] + "\" is in the string \"" + s[i] + "\"")
...     i +=1
...     if i == 5 and j < 5:
...         j+=1
...         i=0
... 
"a b c" is in the string "a b c"
"a b c" is in the string "a b c d"
"a b c d" is in the string "a b c d"
"a b" is in the string "a b c"
"a b" is in the string "a b c d"
"a b" is in the string "a b"
"b c" is in the string "a b c"
"b c" is in the string "a b c d"
"b c" is in the string "b c"
"d" is in the string "a b c d"
"d" is in the string "d"

Answer 4

while循环中的i和j变量不正确。更改值后，代码正常工作。

public class Test_finally {
    private static int run(int input) {
        int result = 0;
        try { 
            result = 3 / input;
        } catch (Exception e) {
            System.out.println("UnsupportedOperationException");
            throw new UnsupportedOperationException("first");
        } finally {
            System.out.println("finally input=" + input);
            if (0 == input) {
                System.out.println("ArithmeticException");
                throw new ArithmeticException("second");
            }
        }

        System.out.println("end of method");
        return result * 2;
    }

    public static void main(String[] args) {
        int output = Test_finally.run(0);
        System.out.println("  output=" + output);
    }
}

Answer 5

保持你的形式：

s = []                                        
s.insert(0,str("a b c"))
s.insert(1,str("a b c d"))
s.insert(2,str("a b"))
s.insert(3,str("b c"))
s.insert(4,str("d"))

j = 0
i = 0

while j < 5:
    if s[j] in s[i]:
        print("\"" + s[j] + "\" is in the string \"" + s[i] + "\"")
    i +=1
    if i == 5 and j <= 4:
        j+=1
        i=0

如果在while循环中，则错误在第2位。它应该是j <= 4或j < 5才能发挥作用。

列表索引超出范围虽然看起来不是

5 个答案:

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