How to get element index of an array?

[algorithmmusic]

Good morning,

I am working on a project where I need to get the element index of an array. The following may clarify this:

char cti[]={'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

If I need the placement number of "5" (which is 6), how do I find this?

Let me know if you need more clarification

[anon56112670]

@algorithmmusic

char cti[]={"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"};

Single quotes, not double.

@algorithmmusic

I need the placement number of "5"

You could look at strchr.

[b707]

@algorithmmusic

placement number of "5" (which is 6),

index of '5' is 5, indexes starts from zero

[alto777]

@anon56112670

Single quotes, not double.

It depends on what @algorithmmusic is talking about.

If you want to find the character 'X' in an array of chars, by hand, you can use a for loop to see if the character at an index i is equal to the character you are looking for.

If you made cti into a properly terminated string, an array of characters with a '\0' in the last index, you could use strchr().

strchr() returns a pointer; to get the index, you must subtract the base array address.

char cti[]={'0', '1', '2', 'A', '4', '5', '6', '7', '8', '9', '\0'};

void setup()
{
  Serial.being(115200);

  Serial.println(cti[3]);

// find 'A'

  char *x = strchr(cti, 'A');
  int index = x - cti;
  Serial.println(index); 
}

void loop()
{
}

HTH

a7

[horace]

you can use a loop to search for the element, e.g.

void setup() {
  Serial.begin(115200);
  int i;
  char cti[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }, find='5';
  for (i = 0; i < sizeof(cti); i++)
    if (cti[i] == find) {
      Serial.printf("index of %c is %d\n", find, i);
      break;
    }
  if (i == sizeof(cti)) Serial.printf("%c not found\n", find);
}
void loop() {
  // put your main code here, to run repeatedly:
}

a run on an ESP32 gives

index of 5 is 5

[algorithmmusic]

How did I forget that