Converting an int or String to a char array on Arduino

Question

I am getting an int value from one of the analog pins on my Arduino  How do I concatenate this to a String and then convert the String to a char     It was suggested that I try char msg     myString getChars     but I am receiving a message that getChars does not exist

User · Accepted Answer

To convert and append an integer  use operator     or member function concat    String stringOne    A long integer     stringOne    123456789   To get the string as type char    use toCharArray     char charBuf 50   stringOne toCharArray charBuf  50     In the example  there is only space for 49 characters  presuming it is terminated by null   You may want to make the size dynamic   Overhead  The cost of bringing in String  it is not included if not used anywhere in the sketch   is approximately 1212 bytes program memory  flash  and 48 bytes RAM    This was measured using Arduino IDE version 1 8 10  2019-09-13  for an Arduino Leonardo sketch

User · Answer

Just as a reference  here is an example of how to convert between String and char   with a dynamic length -      Define  String str    This is my string        Length  with one extra character for the null terminator  int str len   str length     1       Prepare the character array  the buffer   char char array str len       Copy it over  str toCharArray char array  str len     Yes  this is painfully obtuse for something as simple as a type conversion  but sadly it s the easiest way

User · Answer

None of that stuff worked  Here s a much simpler way    the label str is the pointer to what IS an array     String str   String yourNumber  DEC      Obviously    get your int or byte into the string  str   str     r      n      Add the required carriage return  optional line feed  byte str len   str length        Get the length of the whole lot    C will kindly    place a null at the end of the string which makes    it by default an array       The  0  element is the highest digit    so we    have a separate place counter for the array     byte arrayPointer   0   while  str len           I was outputting the digits to the TX buffer      if   UCSR0A  amp   1 lt  lt UDRE0       Is the TX buffer empty                UDR0   str arrayPointer           --str len            arrayPointer

User · Answer

You can convert it to char  if you don t need a modifiable string by using    char   yourString c str      This would be very useful when you want to publish a String variable via MQTT in arduino

[string] Converting an int or String to a char array on Arduino

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