Converting from string to char* on Arduino

Question

The method sprintf() is not valid on Arduino. How else can I convert a string to char*?

 if(triggerNumber == 4)
 { currenttrack = 5;
 }
  sprintf(trackName, "track%03d.mp3", currenttrack);

  playMP3(trackName); //Go play XX.mp3

This link might help, although it is C++, it has close relationship to Arduino programming: link — James
– James, Commented Jul 29, 2014 at 12:40
In standard C++ sprintf is not a method (it is not a member function). It is just a standard function. — Basile Starynkevitch
– Basile Starynkevitch, Commented Jul 29, 2014 at 13:01

Montdidier · Accepted Answer · 2014-07-29 12:58:11Z

1

I believe snprintf will work if you include stdio.h

snprintf(trackName, sizeof(trackName), "track%03d.mp3", currenttrack);

answered Jul 29, 2014 at 12:58

Montdidier

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user3116708 · Accepted Answer · 2014-07-29 14:23:00Z

1

There is a String class in Arduino that you can use. In your case

String trackName = "track";
track += currentTrack;
if (currentTrack < 9) {
    track += currentTrack;
}
else {
    track += "0";
    track += currentTrack;
}
track += ".mp3";
playMP3(trackName);

There are other String manipulation methods in the String class that may be useful. See http://arduino.cc/en/Reference/StringObject

answered Jul 29, 2014 at 14:23

user3116708

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constraintAutomaton · Accepted Answer · 2019-09-10 16:14:40Z

0

you can simply use .c_str().

Returns a pointer to an array that contains a null-terminated sequence of characters (i.e., a C-string) representing the current value of the string object.

http://www.cplusplus.com/reference/string/string/c_str/

answered Sep 10, 2019 at 16:14

constraintAutomaton

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