Question

C语言中输出时怎样控制小数点后的位数，请举例说明

Answer 1

printf("%.2lf",0.123456);只输出小数后2位；
printf("%6.2lf",0.123456);只输出小数后2位；这样可以对齐，保持6位数的位置

Answer 2

A format specification, which consists of optional and required fields, has
the following form:

%[flags]
[width]
[.precision] [{h | l | ll | I | I32 | I64}]type

举个例子：

printf("%.2f", 12345.6789);则会输出12345.67，precision就表示输出小数点后的位数。

Answer 3

在%f前面加上.数字，例如%.2f就是保留两位