What does 100.0F mean? (BME280 Library example)

Projects Programming
1

Hello,

Can someone please help me understand the meaning of “100.0F”. Why is it not 100?

 Serial.print(bme.readPressure() / 100.0F);
Serial.println(" hPa");

The code is from Adafruit BME280 library.

 void printValues() {
    Serial.print("Temperature = ");
    Serial.print(bme.readTemperature());
    Serial.println(" *C");

    Serial.print("Pressure = ");

    Serial.print(bme.readPressure() / 100.0F);
    Serial.println(" hPa");

    Serial.print("Approx. Altitude = ");
    Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
    Serial.println(" m");

    Serial.print("Humidity = ");
    Serial.print(bme.readHumidity());
    Serial.println(" %");

    Serial.println();
}
2

100.0 is a floating point value .
100.0F makes damn sure it's a floating point value.
100 is an integer value.

3

Look up integer and floating point math. There is stuff in the reference above. Weird things happen in code with maths unless you are very specific

4

F suffix implies float type (single precision).
The default, with a decimal point but without a suffix, would be a double.

Most Arduino platforms (Uno, MEGA etc.) only implement single precision floating point (double is implemented using single precision).

There's also the floating point L suffix for long double, but obviously that's not supported on Uno, Mega, etc. either.