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IndexError:使用python3.7时字符串索引超出范围

python

Chris Charley · 技术社区 · 6 年前

程序要求输入几个句子,然后将句子中第一个单词的第一个字母大写。

def main():
    sentence = input('Enter a few sentences (with periods to end them) ')

    s = capitalize_sentence(sentence)

    #print(s)

def capitalize_sentence(s):
    sentences = s.split('.');
    result = ''

    for sentence in sentences:
        # these print as expected no index errors
        #for i in range(len(sentence)): 
        #    print(i, sentence[i])

        if sentence[0] == ' ': # assuming 1 space separates sentences
            result += ' '
            result += sentence[1].upper()
            result += sentence[2:]
            result += '.'
        else:
            result += sentence[0].upper()
            result += sentence[1:]
            result += '.'

    return result

main()

回溯输出为:

“C:/Old\u Data/python/book/ch08/ch08\u ex08\u sentence\u capitalizer.py”,行 29英寸 4,主要 s=大写句子(句)文件“C:/Old\u Data/python/book/ch08/ch08\u ex08\u sentence\u capitalizer.py”,第行 17,大写的句子如果句子[0]='':#假设1空格分隔句子索引器:字符串索引超出范围

谢谢你的帮助。

编辑:我提供的字符串是:你好。你好吗。

3 回复 | 直到 6 年前

Aleph Aleph 6 年前

"howdy. how are you.".split('.')  # = ['howdy', ' how are you', '']

[0] 空字符串的第个字符。在循环中,应该检查句子是否为空并跳过它(例如,使用 continue )如果是:

for sentence in sentences:
    if not sentence:
        continue
    elif sentence[0] == ' ': # assuming 1 space separates sentences
        result += ' '
        # etc.

nosklo 6 年前

您有一个输入字符串,拆分后的句子没有字符。

sentence[0] 失败的原因 sentence "" . 不能获取空字符串的第一个字符。你得到了吗 IndexError: string index out of range .

这个 for 您注释的循环可以工作,因为当字符串为空时,它永远不会进入内部代码块。只会跳过打印任何内容。

我就是这样写函数的:

def capitalize_sentence(s):
   return '. '.join(text.strip().capitalize() 
       for text in s.split('.') if text.strip()) + '.'

测试它:

>>> capitalize_sentence("howdy. how are you.")
'Howdy. How are you.'

Acccumulation 6 年前

def capitalize_sentence(s):
    sentences = s.split('.');
    result = ''
    for sentence in sentences:
        for i, char in enumerate(sentence):
            if char == ' ':
                result +=' '
                continue
            result += char.upper()
            result += sentence[i+1:]
            result+='.'
            break
    return result

def capitalize_sentence(s):
    sentences = s.split('.');
    result = ''
    for sentence in sentences:
        while sentence:
            result += sentence[0].upper()
            if sentence[0] != ' ':
                result += sentence[1:]
                result+='.'
                break
            sentence = sentence[1:]
    return result