Arduino sprintf float not formatting

Question

I have this arduino sketch,

char temperature[10];
float temp = 10.55;
sprintf(temperature,\"%f F\", temp);
Serial.println(temperature);

tem

Answer 1

I've struggled for a few hours on getting this right, but I did finally. And this uses modern Espressif C++ provided by Platformio, and my target MCU is an ESP32.

I wanted to display a prefix label, the float/int value, then the unit, all inline.

I can't relay on seperate Serial.print() statements, as I am using an OLED display.

Here's my code example:

  int strLenLight = sizeof("Light ADC: 0000");
  int strLenTemp = sizeof("Temp: 000.0 °C");
  int strLenHumd = sizeof("Humd: 00.0 %");

  char displayLight[strLenLight] = "Light ADC: ";
  char displayTemp[strLenTemp] = "Temp: ";
  char displayHumd[strLenHumd] = "Humd: ";

  snprintf(strchr(displayLight, '\0'), sizeof(displayLight), "%d", light_value);
  snprintf(strchr(displayTemp, '\0'), sizeof(displayTemp), "%.1f °C", temperature); 
  snprintf(strchr(displayHumd, '\0'), sizeof(displayHumd), "%.1f %%", humidity); 

  Serial.println(displayLight);
  Serial.println(displayTemp);
  Serial.println(displayHumd);

Which displays:

Light ADC: 1777
Temp: 25.4 °C
Humd: 55.0 %