How to get char array's length

Question

I use a LCD display to display a not known size of text ( changes over time ). I wish to display it at the center of LCD ( 2X16 ).

I declare:

 char t[16];
 char h[16];
 sprintf(t, "%.1f%cC %.0f%%", temperature,223, humidity);

Now, since I want to add additional data on a specific line and center it, I need to know it size. When using:

sizeof(t)/(sizeof(t[0])

I get 16 which is the size determined and not its actual size.

How can I get the exact number of chars used?

Answer 1

The function I think you are looking for is strlen - STRing LENgth.

It counts the number of characters in a string up until it finds the "NULL" end of string marker.

Serial.println(strlen(t));

• guyd: well my guess was it refers to String only
• Majenko: strlen is for C strings (NULL-terminated character arrays). For String you want String.length().
• Duncan C: @Guy.D the code you posted is using char arrays, not String objects. Majenko's answer is what you need, not String.length(). Note that you need to be careful not to overflow your char array. That will cause undefined behavior (read "bugs.")