在 Arduino 中将浮点数转换为字符串

Question

I have a few question, how do I convert Float to String?

Because my OLED display require 'String' and cannot print Float

Here is my coding

  WindSpeed = WIND_SPEED_20_PULSE_SECOND / ONE_ROTATION_SENSOR * (float) Rotations;
  float SpeedMPH = ((WindSpeed * 3600) / CONVERTMPH_FORMULA);
  String WindSpeedMS = WindSpeed;
  if((millis() - Start_Read_Timer) >= READ_TIME)
  {
    cli();

    WindSpeedStatus();
    
    sei();

    Rotations = 0;
    Start_Read_Timer = millis();
  }
    display.setFont(ArialMT_Plain_24);
  display.drawString(0, 20, WindSpeedMS);
  display.display();
  delay(500);

The error I got is:

Compilation error: conversion from 'float' to non-scalar type 'String' requested

Thanks!

Answer 1

Try

float SpeedMPH = ((WindSpeed * 3600) / CONVERTMPH_FORMULA);
String WindSpeedMS = String(SpeedMPH,0); // 2nd param is decimal digits 

Answer 2

refer to Arduino String library as they stated that:

Syntax

• String(val)

• String(val, base)

• String(val, decimalPlaces)

Parameters

• val : a variable to format as a String. Allowed data types: string, char, byte, int, long, unsigned int, unsigned long, float, double.

• base : (optional) the base in which to format an integral value.

• decimalPlaces : only if val is float or double. The desired decimal places.

so instead of writing:

 String WindSpeedMS = WindSpeed;

you should write:

String WindSpeedMS = String(WindSpeed, 5);

where 5 represents the number of decimal places desired, so if WindSpeed = 12.54545451 then WindSpeedMS = "12.54545"