Python：從字符串的結尾開始返回索引的函數

Question

是否有函數返回結束索引而不是子字符串的開始索引。例如，對於

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

string.foo('mainly ')返回31，而不必使用string.index('mainly ')+len('mainly ')？

Answer 1

它可以在兩線可以輕鬆實現：

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