Negative expressions are printed with a leading minus sign. If a certain range is exceeded for floating-point values, the respective numerical expression is printed in exponential notation.
打印的正数表达式前面带有一个空格，而打印出的负数表达式前面带有一个减号。对于超出了浮点数取值范围的数字表达式，则以指数表示法打印。