X的浮点精度

Question

这不是代码修订版，因此我在这里创建了线程。我的任务如下：

Write a program which: 1. intializes a variable a with 123, and prints the value of a over 7 places, 2. intializes a variable b with -89.6548754, and prints the value of b over 10 places and with a floating point precision of 4

第一个是：

a = 123
print("The value is {0:7d}".format(a))

我不明白的是第二个。什么是“浮点精度4”？这是什么意思？我想这意味着要把小数位数（即7（6548754））缩短到4。你知道吗

b=-89.6548754
print("The value is {:10.4f}".format(b))

Answer 1

从format string mini-language specification：

The precision is a decimal number indicating how many digits should be displayed after the decimal point for a floating point value formatted with 'f' and 'F', or before and after the decimal point for a floating point value formatted with 'g' or 'G'. For non-number types the field indicates the maximum field size - in other words, how many characters will be used from the field content. The precision is not allowed for integer values.

是的，它是小数点后的位数。你知道吗