Questions tagged [string]

A sequence of characters -- including letters, numbers and symbols -- often used for representing information in a human-readable format.

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82 views

Possibility of clean the code?

Good night! Based on stuff I get a bit here and there, came up with a program for an Arduino Audio Selector with shift registers and some features. Working as expected, only missing connecting the ...
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2answers
114 views

Does toCharArray prevent a String being created on the heap?

I know it's bad to use Strings due to the memory problems that can occur. I've tried to remove all instances of strings from my code. But I'm not sure about this line: http.getString().toCharArray(...
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3answers
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How to fix memory-leak code in ESP8266/NodeMCU caused by string concenation?

I have following code in loop() in NodeMCU. This part is before setup(): String serial_data_read = ""; // for incoming serial string data String serial_data = ""; // for incoming serial string ...
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2answers
446 views

Convert comma-delimited Arduino String of hex values to array of bytes

My apologies if this is a naive question. How do I convert a String which has hex values to a byte array that has those hex values? This: String s = "0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff"...
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3answers
665 views

How to replace String objects with char arrays while still using string methods

I am running the following code on my ESP8266 (AI-Thinker ESP8266MOD). I send an HTTP GET request and a pin is set to high for a 1/2 second. However, after some time (sometimes 1hr, 2hrs, 12hrs, ...
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1answer
457 views

Scrolling an I2C text

I want tried to make a programm to display a text on an I2C LCD-Display. The text should be scrolled for one position every time the function is called. On the internet I saw a lot of solutions but ...
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1answer
50 views

How to assign a string-variable to a StackString based on the StackString-library?

I'm trying to use the StackString-library which offers not to eat up RAM over time by re-assigning values to strings. I started from scratch and wrote a very basic democode which works. Then I added ...
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2answers
37 views

Regarding Strings and assignments

I have this code which works : String ErrorMsg; ....... if(!UploadPacketError) { ErrorMsg="OK"; } else { ErrorMsg="NOK"; } String creates a dynamically allocated array which I want to avoid. ...
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2answers
831 views

Clearing string buffer with memset after a serial read

In using the SerialTransfer.h / pySerialTransfer libraries to send commands between my laptop and an Arduino Mega, I am sending multiple sequential strings between the devices. However, I'm having ...
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0answers
37 views

Split string using a delimiter then saving to different variables [duplicate]

I have a string that looks something like this "43;27;42;27". It is the data from 4 DHT22 temperature sensors, i need to splice this string every ";" and save the number to a variable. In the end, I ...
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2answers
104 views

Unpredictable behavior on parsing key-value delimited input from serial

I am having trouble with a "simple" command parser; I'm guessing I'm doing something wrong with memory allocation - appreciate any pointers :) For context: I'm running on an Arduino Uno (if it ...
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3answers
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Copying String into another String

I have an array of Strings in my code: String BitSequence [257]; Each string will have 23~64 characters. At one point in my code, I have to use "myString.remove()" command and I don't want to apply ...
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2answers
562 views

Reading from SPIFFS - What's the best way to deal with a string (or char) array with undefined length?

I've read that it's best to avoid using String in Arduino so I'm ready to use a char array if it's better. I'm reading the file names from an SD Card and my goal is to store them in an array and then ...
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1answer
791 views

Convert JSON into string for MQTT

I am trying to publish json object into string with following snippet JSONVar data; data["chipid"] = chipId; data["co2_equivalent"] = co2_equivalent.c_str(); data["tvoc"] = tvoc.c_str(); data["...
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0answers
50 views

ESP8266 EEPROM Reading extra character

I am very very new to ESP Programming. I am trying to store Strings into EEPROM of ESP8266. I am storing the string into eeprom successfully but while reading it from EEPROM extra character 'd' is ...
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1answer
59 views

Running commands from string

I have a string: string s="digitalWrite(8,LOW);" Is there any way to run it as a code?
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1answer
406 views

Scroll Left to Right on MAX7219 Display

For scrolling from left to right (Arabic letters) I need a function to print words/sentences on the MAX7219 display. [By setpixel(x, y) function] I did a lot of searching and my efforts failed. I ...
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4answers
1k views

String to float on Arduino

I'm trying to convert a String to a float but I'm running into issues with precision, even with the Arduino's own String example I'm getting bad results. Example 0: Input string: 1.234567 After ...
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2answers
96 views

Mixed structure with int and string

I want to create a structure like this: struct commands { int cmd; char descr[25]; }; commands cmds[] = { {16, "Hammond Organ"}, {17, "Percussive Organ"}, {18, "Rock Organ"}, { 0, "" ...
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1answer
73 views

Comparing a text string to text output (DHT22)

Lately I've received a DHT22 sensor. I've started to create a small temperature and humidity monitor station. One of the things I noticed was if you pulled out the sensor while in use, it displayed "...
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1answer
65 views

String generator not working as expected

I'm trying to build a random string, save it to EEPROM as int, then read it back and output it. If I give it a predefined string then it works fine. But Something is wrong with the random string ...
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0answers
39 views

How to compare an incoming byte from cool terminal as modbus hex value and compare it with a predefined value in set in the program?

My Input from Cool terminal is 05 03 00 01 00 02 94 4F I should be able to read this input 05 03 00 01 00 02 94 4F compare with the same(05 03 00 01 00 02 94 4F). If the incoming value(05 03 00 ...
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1answer
1k views

Convert float to hexadecimal value

I am trying to convert a float value to a 4-byte hexadecimal value. For example my input is: 58.5. My expected output is: 426A0000 or like 0x42 0x6A 0x00 0x00. My program is: void setup() { ...
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1answer
31 views

I can't receive string that I have sent through nrf correctly

I'm using arduino uno and nrf24l01. to monitor sensor data. But this is the message that master receives: ⸮ this is my slave code. void monitoring() { delay(10); radio.stopListening(); ...
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1answer
598 views

Arduino - Extracting Multiple Strings from Serial Read

I am trying to write an Arduino code that reads a long string, example <11,22,33>, through the Serial Monitor and then stores the 11,22, and 33 into separate bins of a matrix array. So the user ...
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2answers
147 views

Yet another basic and silly question about C++ strings

I made a sketch like this: void setup() { // put your setup code here, to run once: Serial.begin(9600); char str1[64] = "test with spaces"; char str2[32] = "test with spaces"; Serial....
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2answers
570 views

How to Sort a String with Number by Ascending

I have trouble figuring out how to sort a String that has a Number in it. The String im sending looks like 112:AAAA and 111:EEEE, how would I sort it so that the 111 will be the first in an array but ...
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1answer
147 views

How to decrease delay for String concatenation + Arduino Due

In my project I need to add a delimiter between integer numbers. In the following code. I add a "," between integer numbers obtained from inputsig matrix. The problem is that concatenation of these ...
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1answer
2k views

char buffer to String in Arduino UNO

String getAPIData() { char res_buffer[450]; int numdata = inet.httpGET("myserver.com", 80, "/call.php?id=1&q=1&code=1001", res_buffer, 450); String result = String(res_buffer); Serial....
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1answer
353 views

Second item in array not gets assigned from struct object, ArduinoJson

I got the below code generated this amazing tool. const size_t capacity = JSON_ARRAY_SIZE(2) + JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(4) + 2*JSON_OBJECT_SIZE(7); DynamicJsonDocument doc(capacity); ...
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4answers
6k views

Convert String to IPAddress

How can i convert a String to IPAddress on arduino / esp ? etc. "192.168.1.2" -> IPAddress(192, 168, 1, 2) Tried this void setup() { Serial.begin(115200); IPAddress apip; const char *...
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1answer
35 views

arduino mega multi integer values reading on other arduino mega

I need two Arduino communications. The master arduino from the slave arduino needs to read 16 signals. The sample serial port output from the slave is as follows. @ 125 @ 13 @ 874 @ 1023 & 950 @...
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3answers
245 views

How to actually concatenate two Strings?

I'm using the SPISlave library, and I have the following code snippet: String arg; SPISlave.onData([arg](uint8_t *data, size_t len) { data[len] = 0; arg += String((char *)data); // ... } The ...
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2answers
269 views

How do I implement reverse enumeration?

Basically I'm trying to output a string based upon a value in an array, the following code is what I have come up with to achieve my desired result, but I have a feeling that there is a better way to ...
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0answers
35 views

How to create parametric variable in class decleration

I hope the subject of this question if correct. in timeOUT constructor, 3 more instances of other class are defined: endTimeOUT_inFlash(key1), inCodeTimeOUT_inFlash(key2), updatedTimeOUT_inFlash(...
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1answer
75 views

Update `char* `

I have a class containing few char* variables: char* msgTopic = "myHome/MSGS"; char* groupTopic = "myHome/All"; char* errorTopic = "myHome/Err"; but, I wish to have it defined outside the ...
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1answer
1k views

From Strings to int problem

I create applications for a computer that is to be used to control the robot arm. I wanted to make the first attempt to run the application not on the motor, but on the diode and check if it will ...
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2answers
525 views

Parsing Arduino Receiving Strings

I'm currently using google geolocation to get location data to one nodemcu and sending it through serial to another Arduino. The serial command I'm getting right now is, 1.450187T103.824745 I'm ...
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1answer
66 views

How to stringtok this long string? [closed]

I have a string, "id,port,password,ssid,delay,flag,class,category" Please tell me how can stringtok this and find out the "flag" value(0 or 1)? Here is what I tried: void setup() { char input[]...
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1answer
202 views

Change data-type String

I'm currently working with an ESP8266 NodeMCU V3 and an IR transmitter breakout board. The module receives NEC IR commands trough a HTTP request and then sends them trough the IR transmitter. Getting ...
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0answers
134 views

BLE splitting string data

I am working with BLE 4.2 (ESP32) that sends IMU (accel, gyro, mag) data to my mobile app (Android). Unfortunately, I can send only 20 bytes in one packet. This is the code I have: (I am connecting ...
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0answers
123 views

Sensor to detect whether string is in tension?

I need a sensor to detect whether there is tension on a string or not. I do not need an accurate measurement of the amount of tension- just whether the string is being pulled on or is taut. ...
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2answers
874 views

Compute SHA256 of string and output to string

In my Arduino project I want to compute the SHA256 hash of a string and store the result to a string, and do this recursively many times (i.e. compute hash of hash of hash etc...). So my goal is to ...
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0answers
864 views

string.charAt() is not returning the correct value

I know this is a super basic question, and I did try debugging, but somehow I think I am missing the way variable stores value in Arduino. int enablePin = 2; // ebanble pin for slave String ...
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1answer
5k views

How to compose an HTTP GET request URL with key/value parameters

I am experimenting with some code running on an ESP8266 board to retrieve data using a web API. I would like to store the host address and key/value parameters (API key etc.) of the GET request as ...
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1answer
395 views

Send Strings via SPI both ways using two Arduino UNOs(Master to Slave & Slave to Master)

I need to create a two way String exchanger via SPI with two Arduino UNOs. Strings and their lengths are independent variables of the main loop and they can change with every iteration. I need both of ...
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0answers
275 views

Compare barcode scanner string with existed string

I have a project which is reading barcode scanner result then compare with an existed string. I have used the library USB host shield in order to read data from barcode scanner then I would like to ...
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1answer
343 views

ESP8266 crashes when trying to copy a string into a big char

I'm trying to parse with tinyxml2 a modest XML (3.4kb) to retrieve some data. My ESP8266 crashes every time I try to use the toCharArray method. here's my code // here I'm getting an http request ...
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1answer
502 views

Problem with String& argument of a function

I am trying to send SMSs using a GSM module with Arduino Mega. I have followed a tutorial and downloaded the SIM908IDE100 library. I am using the function SendSMS(String&, const char [27]);. It ...
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5answers
7k views

How to compare a string

How to compare a string coming from serial monitor with some predefined text stored as a local variable? If I say: int led = 2; String a = " abcds"; void setup(){ Serial.begin(9600); } void loop(...

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