C++ 使用 printf 打印浮点数时额外的前导零？
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Extra leading zeros when printing float using printf?
提问by shoosh
I'd like to be able to write a time string that looks like this: 1:04:02.1 hoursusing printf.
When I try to write something like this:
我希望能够编写一个如下所示的时间字符串：1:04:02.1 hours使用 printf。
当我尝试写这样的东西时：
printf("%d:%02d:%02.1f hours\n", 1, 4, 2.123456);
I get:
我得到：
1:04:2.1 hours
Is it possible to add leading zeros to a float formatting?
是否可以将前导零添加到浮点格式？
回答by AndiDog
With the %fformat specifier, the "2" is treated as the minimum number of characters altogether, not the number of digits before the decimal dot. Thus you have to replace it with 4 to get two leading digits + the decimal point + one decimal digit.
对于%f格式说明符，“2”被视为最小字符总数，而不是小数点前的位数。因此，您必须将其替换为 4 才能获得两位前导数字 + 小数点 + 一位小数。
printf("%d:%02d:%04.1f hours\n", 1, 4, 2.123456);
回答by kennytm
Try %04.1finstead of %02.1f. The "4" here means at least 4 characters will be printed, and "2.1" has 3 (> 2) characters, so to enable the padding zeros you need 4.
尝试%04.1f代替%02.1f. 这里的“4”表示至少会打印 4 个字符，而“2.1”有 3 (> 2) 个字符，因此要启用填充零，您需要 4 个。
