str. ljust(width[, fillchar])
str. rjust(width[, fillchar])
str. center(width[, fillchar])
空格
)。str_ = 'Nanjing'
# fillchar = '+'
assert str_.center(10, '+') == '+Nanjing++'
assert str_.ljust(10, '+') == 'Nanjing+++'
assert str_.rjust(10, '+') == '+++Nanjing'
# fillchar: default is a space
assert str_.center(10) == ' Nanjing '
assert str_.ljust(10) == 'Nanjing '
assert str_.rjust(10) == ' Nanjing'