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

Possible duplicate of http://stackoverflow.com/a/7391187/3093378 — vsoftco, Jul 29 '14 at 12:37
This link might help, although it is C++, it has close relationship to Arduino programming: [link](http://stackoverflow.com/questions/9309961/how-to-convert-string-to-char-in-c) — James, Jul 29 '14 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, Jul 29 '14 at 13:01

score 1 · Accepted Answer · answered Jul 29 '14 at 12:58

1

I believe snprintf will work if you include stdio.h

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

answered Jul 29 '14 at 12:58

Montdidier

1,181
1
8
21

score 1 · Answer 2 · answered Jul 29 '14 at 14:23

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

score 0 · Answer 3 · answered Sep 10 '19 at 16:14

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 '19 at 16:14

constraintAutomaton

151
7

Converting from string to char* on Arduino

3 Answers3