Python：从字符串末尾返回索引的函数

Question

是否有函数返回结束索引而不是子字符串的开始索引。 例如，对于

string = 'the rain in spain stays mainly in the plain'

string.foo('mainly ') string.index('mainly ')+len('mainly ') string.foo('mainly ')返回31，而不是必须使用string.index('mainly ')+len('mainly ')吗？

Answer 1

它可以通过两行轻松实现：

def get_sub_end(s, sub):
    f = s.find(sub)
    return f if f == -1 else f + len(sub)

用法：

test_str = 'the rain in spain stays mainly in the plain'

if __name__ == '__main__':
    print get_sub_end(test_str, "mainly ")  # >>> 31
    print get_sub_end(test_str, "undefined ")  # >>> -1