如何将串行输入存储在字符数组 arduino 中？

Question

My aim was getting some parts of a char array between 2 specified characters. The code below perfectly works and returns 0037 as I expected. However I wanted to make it useable with serial input not only char*s. In other words if I write "123123123,0037sjd#asdasdasd" to the serial. the code should work in a same way again.

How can I do that?

const char *s = "123123123!0037sjd#asdasdasd";
const char *CHAR1 = "!";
const char *CHAR2 = "#";
char *target = NULL;
char *start, *end;

void setup() {
  Serial.begin(9600);
}

void loop() {
  //s=(char)Serial.read();
  if (start = strstr(s, CHAR1)) {
    start += strlen(CHAR1);
    if (end = strstr(start, CHAR2)) {
      target = (char*) malloc(end - start + 1);
      memcpy(target, start, end - start);
      target[end - start] = '\0';
    }
  }
  if (target) {
    for (int i = 0; i < 4; i++) {
      Serial.print(target[i]);
    }
    target = "";
    free(target);
  }
  target = "";
  free(target);
}

Answer 1

Assignment loses original allocation.

Code errantly free's something not allocated.

// Bad
target="";        // loses prior allocation
free( target );   // Attempts to free something not allocated

Instead

free( target );
target = NULL;

Answer 2

For parsing a serial stream like that, maybe just use a flag. Start off with the flag cleared. When you see a ! set the flag. When digits come in while the flag is set, store them in the array. When you see something that's not a digit, clear the flag.

You could even accumulate the digits in an integer on the fly (skipping the array), if that's what the end result will be.

Personally, I don't use malloc/free on the Arduino, and it's not really needed here.

HTH!