Questions tagged [c-string]

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98 views

Mqtt not subscribe on topic that's converted from String to char array

I am still not sure what should be the exact Title for this question, because I don't know where the problem is. I am using #include <MQTTClient.h> mqtt library to subscribe on a topic. This ...
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1answer
829 views

Splitting a Serial.readString into string array

I am working on a project where I need to split incoming data from serial (time to be exact, so aa:bb:cc) and need to split it into aa then bb and cc, ideally into an array. I know I could use ...
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1answer
326 views

Using c_str() on String for IPAddress with NTPClient provides wrong values

Libraries NTPClient Board Olimex ESP32-POE board Behaviour I have written a code that connects the board to a local NTP Server (which is an embedded board). I tried assigning the IP Address of ...
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2answers
2k views

Problems on convert byte[] to String

I'm reading a RFID Card from RC522 and send the data to my computer. My problem is the conversion of byte[] to String or std::string. #define SIZE_BUFFER 18 #define MAX_SIZE_BLOCK 16 byte ...
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3answers
1k views

formatting strings in Arduino for output

I wander what is the best option for formatting strings in Arduino for output. I mean what's a preferable way in the point of view of performance, memory usage – things like that. I see, people ...
1
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1answer
2k views

Char* and string conversion from an ESP8266 web server

I have the following Arduino code for configuring a wifi connection through a simple webpage: I declare char* ssid;. Later I read a value from a SPIFFS config file where q_ssid is declared as a ...
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2answers
1k views

Arduino GSM module + SMS string sending garbage value

I want to check the water level and have an SMS sent via a GSM module. Reed switches are connected to four Arduino analog inputs. I am unable to add a string and tank level (TKLVL) in program. The ...
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2answers
2k views

Max length of char arrays?

I'm running the following Sketch on my Arduino Uno: const boolean verbose = true; void debug(const char *s){ if(verbose){ char buf[8 + sizeof(s)] = "[DEBUG] "; strcat(buf, s); ...
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1answer
651 views

Store 3-dimensional char array in program memory with PROGMEM

I'm running a sketch whith a quite big, constant three dimensional char array (or simply, a table of strings). As this takes lots of RAM I'd like to store it in programm memory in order to keep the ...
3
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1answer
41k views

Convert int to char[]

I'm looking to convert an int value to a char array. currently I've found the following will return [number] int num = [number] str = String(num); str.toCharArray(cstr,16); Serial.println(cstr); ...