Questions tagged [strlen]

Returns the length of the C string str. The length of a C string is determined by the terminating null-character: A C string is as long as the number of characters between the beginning of the string and the terminating null character (without including the terminating null character itself). Source: http://www.cplusplus.com/reference/cstring/strlen/

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How to get char array's length

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%%"...
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strcat parameters throwing pointer errors in my tcp server / parser application

I am attempting to use an Arduino Uno WiFi Rev2 board to integrate some lonely data. I will use the NINA WiFi chipset and associated libraries to start a server that will periodically request and ...
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72 views

Arduino scrolling text program freeze after some time

I use a 16x2 character lcd to display some text. What I want is first line will stay, but the second line should scroll text. I wrote a program which works fine but the problem is after some time ...
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409 views

String & Char concatenations

A newbie in Arduino- and I'm trying to concatenate string and chars ( well in python it is quite different ). I'm trying to post a MQTT message- constructed following format to the client.publish(...
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1answer
773 views

POST request on Arduino MKR1400 GSM not working

Im trying to send a POST request from the Arduino MKR1400 GSM board to a server with a database. I've tested the server using Postman (https://www.getpostman.com/) and it handles the POST request ...
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1answer
588 views

Arduino IDE: How to get PROGMEM const length?

I have defined a byte array as a constant in the Atmel's flash memory: const uint8_t eye [] PROGMEM = { 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff }; How ...
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1answer
458 views

Arduino keypad and RF 433MHz transmitter problem

So, the basic idea is that user presses a key on keypad, and key that is pressed is sent with RF transmitter. I got individual parts to work(keypad and transmitter), but can't send the actual key. ...
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2answers
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Arduino to arduino serial communication without a library

So I'm trying to send an array from one arduino to another through serial communication, without using the software serial library. The arduinos are wired rx->tx, tx->rx and ground to ground. I have a ...
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3answers
24k views

Number of elements in an array char

What kind of function can I use to know how many elements are in an array char? sizeof() gives the number of 'spaces' available so it doesn't work for me.
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9k views

Why can't this C++ program read my arduino's Serial.write()?

I made a super simple arduino uno sketch to send a serial byte once every second: void setup(){ Serial.begin(9600); } void loop(){ Serial.write(12); // send a byte with the value 12 delay(...