CODEWITHSUNDEEP
c++arduino
ricoen
ricoen

Reputation: 9

Get the right size of a char array string

I want to get the size of an array from return value of a function. This is the function:

const char* bukaKunci(){
  if(mlx.readObjectTempC() >= tempMin){ // if temp is lower than minimum temp
    digitalWrite(selenoid, HIGH);
    delay(1000);

    return "Kunci terbuka!";
  }
  else{
    digitalWrite(selenoid, LOW);
    delay(1000);

    return "Pintu terkunci"; 
  }
  return 0;
}

But when I check the size with this line:

const char* msg = bukaKunci();
  int msg_len = sizeof(msg);

  Serial.println(msg);
  Serial.println(msg_len);

It gives me output the size of msg is 2, like this:

Kunci terbuka!
2

Did I missing something?

Upvotes: 0

Views: 438

Answers (2)

Bouraoui Al-Moez L.A
Bouraoui Al-Moez L.A

Reputation: 989

If you want to get the length of a C string pointed at by a char*, you can use strlen(). sizeof() is used to get the size of a type. As msg is a pointer, you will get the size of the pointer, not the length of the string it is pointing at.

char msg [100] = "bar";
Serial.println (strlen (msg))

Upvotes: 1

Umar Farooq
Umar Farooq

Reputation: 416

int msg_len = sizeof(msg);

the above line of your function is returning the size of the object of the pointer and via pointer you can not determine the size of the array . May be you should read about a array decay.

Two possible solutions .

  1. Iterate over the array with a counter and counter will tell you the exact size
  2. use built in function like
strlen(msg)

will solve your problem

Upvotes: 1

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