PHP - 如何获得API值的一致输出 - 浮点数具有特定的小数位数

Question

My API request currently returns JSON in the following format:

[
  {
    "date":"2016-08-11",
    "voltage":0.1,
    "current":0.01,
    "power":0,
    "energy": null,
  }
]

I'm trying to ensure consistency of data output by forcing the voltage, current and power values to be three decimal places, type float. I've tried using number_format() but the output are type strings, which I do not want. Is there a way of doing this, i.e. outputting 0 as a float 0.000 rather than staying an integer? Also, when no values are present I need to convert null into 0.000, is that possible without casting to strings?

The question PHP float with 2 decimal places: .00 doesn't explain (in layman's terms) why this is not possible in PHP.

Answer 1

echo floatval(number_format('0.001', 3)); // output: float 0.001

But unfortunately strings containing '0.000' or null after type casting will produce 0.

echo (float)number_format('0.000', 3); // output: 0
echo floatval(number_format('0.000', 3)); // output: 0
echo floatval(number_format(null, 3)); // output: 0

"...bytes with value 0 (“NUL bytes”) are allowed anywhere in the string (however, a few functions, said in this manual not to be “binary safe”, may hand off the strings to libraries that ignore data after a NUL byte.)" Details of the String Type

You may handle output at the presentation layer instead.