# Float to uint8\_t **URL:** \ **Category:** Programming\ **Created:** [February 1, 2020, 10:04pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399 "2020-02-01T22:04:17Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![carlos14](https://avatars.discourse-cdn.com/v4/letter/c/d07c76/32.png) [@carlos14](https://forum.arduino.cc/u/carlos14)\ **Post date:** [February 1, 2020, 10:04pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/1 "2020-02-01T22:04:17Z")
```cpp I have two variables uint8_t charData[6]; float Fahrenheit = 0; I need to convert the float value to an uint8_t type. The float value comes from a temp sensor, DS18B20, for example, 74.53 sensors.requestTemperatures(); Celcius = sensors.getTempCByIndex(0); Fahrenheit = sensors.toFahrenheit(Celcius); Elsewhere in the code, to convert the float value to uint8_t, among many other things I tried: dtostrf(Fahrenheit, 0, 5, charData); also: String sensorData = String(Fahrenheit); sensorData.toCharArray(charData, sensorData.length() + 1); One may think that doing this should be very simple, but I have not been able to figure it out. Can anyone help, please? ``` ---
**Author:** ![UKHeliBob](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ukhelibob/32/215663_2.png) [@UKHeliBob](https://forum.arduino.cc/u/UKHeliBob)\ **Post date:** [February 1, 2020, 10:13pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/2 "2020-02-01T22:13:21Z")
What you expect the value 74.53 to be assuming that you manage to convert it into a byte ? ---
**Author:** ![carlos14](https://avatars.discourse-cdn.com/v4/letter/c/d07c76/32.png) [@carlos14](https://forum.arduino.cc/u/carlos14)\ **Post date:** [February 2, 2020, 3:25am UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/3 "2020-02-02T03:25:33Z")
```cpp I am sorry, I don't understand the question. However, what I am trying to do is to send the value to the Adafruit IO platform. I included Adafruit's Adafruit_MQTT and Adafruit_MQTT_Client libraries. I did the setup following the sample code: Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY); Adafruit_MQTT_Publish publishData = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME "/feeds/myFirstValue"); and later in the code I am trying to publish the value: if (! publishData.publish(charData)) {   Serial.println(F("Failed")); } else {   Serial.println(F("OK")); } I hope my explanation makes sense. Thank you, ``` ---
**Author:** ![DrAzzy](https://avatars.discourse-cdn.com/v4/letter/d/eb9ed0/32.png) [@DrAzzy](https://forum.arduino.cc/u/DrAzzy)\ **Post date:** [February 2, 2020, 3:56am UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/4 "2020-02-02T03:56:04Z")
a uint8\_t is a byte - a single value between 0 and 255. It sounds like you are trying to convert it to a c string (array of characters) - which is an array of characters (int8\_t). This all suggests that there is some confusion on your part about what you have to do. What makes you think it should be a uint8\_t? Is there some error message that is suggesting that, or what? A quick look at that library shows that there is no publish() method that takes a uint8\_t array like you are attempting to pass it (though you haven't told us what version you are using - popular libraries often have many versions on various peoples' github with significant differences, so you need to specify where you got it from). In fact, the version I am looking at has a publish() method that takes a floating point number.... ---
**Author:** ![GolamMostafa](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/golammostafa/32/239011_2.png) [@GolamMostafa](https://forum.arduino.cc/u/GolamMostafa)\ **Post date:** [February 2, 2020, 3:58am UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/5 "2020-02-02T03:58:12Z")
**union** data structure could be used to convert a float number into 32-bit (4-byte) binary32/IEEE-754 formatted data and vice versa. For example: ```cpp union {    float Fahrenheit;    uint8_t myData[4];     //low order member holds low order byte (little endianness) }myTemp; myTemp.Fahrenheit = 74.53; ``` ---
**Author:** ![GoForSmoke](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/goforsmoke/32/1127097_2.png) [@GoForSmoke](https://forum.arduino.cc/u/GoForSmoke)\ **Post date:** [February 2, 2020, 5:18am UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/6 "2020-02-02T05:18:16Z")
> carlos14: > I have two variables > > uint8\_t charData[6]; > float Fahrenheit = 0; > > I need to convert the float value to an uint8\_t type. Just for starts; code tags are for code, not the whole post. Your variables tell me you want convert float to text as uint8\_t (also named byte). Why not type char, int8\_t, since C libraries functions use type char for strings? Since you know the max temperature will be less than 1000, char number[10]; // float may be 7 places plus decimal point plus sign if negative and terminating zero. * * * _But really the only time you convert variable to text is to print to screen or file._ _You don't -need- the string at all, it is a waste of RAM since there are numeric ways to pull sign and each digit out of that float._ _-----------------------------------_ _I'd start by loading 100 x Farenheit into a long which rounds off past 2 places and ends slow sand-and-dirt floating point math._ _```_ \*//  untested, never compiled but the logic is old hat to me long X, tmp; // --- and inside of a printTemperature function X = (long)( Farenheit \* 100.0); if ( X \< 0 ) {   Serial.write( '-' );   X = -X; } if ( X \>= 10000 )  // 100F in 100ths of 1F {   tmp = X / 10000;   Serial.print( tmp );   X -= tmp \* 10000; } if ( X \>= 1000 )  // 10F in 100ths of 1F {   tmp = X / 1000;   Serial.print( tmp );   X -= tmp \* 1000; } if ( X \>= 100 )  // 1F in 100ths of 1F {   tmp = X / 100;   Serial.print( tmp );   X -= tmp \* 100; } else {   Serial.write( '0' ); } Serial.write( '.' ); if ( X \>= 10 )  // 0.1F in 100ths of 1F {   tmp = X / 10;   Serial.print( tmp );   X -= tmp \* 10; } else {   Serial.write( '0' ); } if ( X \>= 1 )  // 0.01F in 100ths of 1F {   tmp = X / 10;   Serial.print( tmp );   X -= tmp \* 10; } else {   Serial.write( '0' ); }\* _```_ _It could be shortened with a little trouble but it adds a lot less to the code size than sprintf() and uses very little RAM._ _It might even run quicker... there's a fast divide by 10 routine in the Arduino Playground that'd make that pretty certain._ ---
**Author:** ![carlos14](https://avatars.discourse-cdn.com/v4/letter/c/d07c76/32.png) [@carlos14](https://forum.arduino.cc/u/carlos14)\ **Post date:** [February 2, 2020, 8:59pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/7 "2020-02-02T20:59:07Z")
As @DrAzzy suggested, I am trying to convert from float to int8\_t. As you may have noticed, I am not very proficient in C or C++. I still don't know how to do the conversion. Thank you @GoForSmoke for the clarification about code tags. Thank you everybody else for your comments. ---
**Author:** ![Idahowalker](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/idahowalker/32/238858_2.png) [@Idahowalker](https://forum.arduino.cc/u/Idahowalker)\ **Post date:** [February 2, 2020, 9:23pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/8 "2020-02-02T21:23:23Z")
here is a snippet that I use to break down a 32 bit number into 4 bytes (unit8\_t) ```cpp rx_frame.data.u8[0] = *item & 0xFF;           rx_frame.data.u8[1] = (*item >> 8) & 0xFF;           rx_frame.data.u8[2] = (*item >> 16) & 0xFF;           rx_frame.data.u8[3] = (*item >> 24) & 0xFF; ``` ---
**Author:** ![UKHeliBob](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ukhelibob/32/215663_2.png) [@UKHeliBob](https://forum.arduino.cc/u/UKHeliBob)\ **Post date:** [February 2, 2020, 9:32pm UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/9 "2020-02-02T21:32:40Z")
> As @DrAzzy suggested, I am trying to convert from float to int8\_t > I still don't know how to do the conversion. Let's try to find out what you really want to do Given a float, say 1234.56, what do you expect it to look like when converted to uint8\_t and how many bytes will be required to hold the result ? ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [May 6, 2021, 12:17am UTC](https://forum.arduino.cc/t/float-to-uint8_t/634399/10 "2021-05-06T00:17:25Z")
Closed on May 6, 2021, 12:17am UTC