str.format() 选项不起作用

Question

此代码取自教程：

def main():
    stri = "Hello, {person}"
    stri.format(person="James")
    print(stri) #prints "Hello, {person}"

为什么format() 不起作用？

Answer 1

确实有效。您只是没有将格式分配给变量，然后只是打印原始字符串。请参见下面的示例：

>>> s = 'hello, {person}'
>>> s
'hello, {person}'
>>> s.format(person='james')
'hello, james'                    # your format works
>>> print s                       # but you did not assign it
hello, {person}                   # original `s`
>>> x = s.format(person='james')  # now assign it
>>> print x 
hello, james                      # works!