如何使用函数从字符串中提取第一个、第二个和最后一个单词？答案

【问题标题】：How to extract 1st, 2nd and last words from the string using functions?如何使用函数从字符串中提取第一个、第二个和最后一个单词？
【发布时间】：2021-12-27 00:31:05
【问题描述】：

我的程序只提取字母，而不是整个单词。

def first_word(sentence):
    return sentence[0]
def second_word(sentence):
    return sentence[1]
def last_word(sentence):
    return sentence[-1]
  
if __name__ == "__main__":
    sentence = "I want to learn python"
    print(first_word(sentence))
    print(second_word(sentence))
    print(last_word(sentence))

上面示例中的输出必须是：

I
want
python

【问题讨论】：

标签： python string function

【解决方案1】：

使用str.split方法：

def first_word(sentence):
    return sentence.split()[0]  # <- HERE
def second_word(sentence):
    return sentence.split()[1]  # <- HERE
def last_word(sentence):
    return sentence.split()[-1]  # <- HERE
  
if __name__ == "__main__":
    sentence = "I want to learn python"
    print(first_word(sentence))
    print(second_word(sentence))
    print(last_word(sentence))

输出：

I
want
python

【讨论】：

【解决方案2】：

sentence.split() 将返回由空格分隔的所有单词的列表：

def first_word(sentence):
    return sentence.split()[0]
def second_word(sentence):
    return sentence.split()[1]
def last_word(sentence):
    return sentence.split()[-1]

if __name__ == "__main__":
    sentence = "I want to learn python"
    print(first_word(sentence))
    print(second_word(sentence))
    print(last_word(sentence))

【讨论】：