Questions tagged [string]
A sequence of characters -- including letters, numbers and symbols -- often used for representing information in a human-readable format.
1
vote
2answers
41 views
How to combine strings and text together?
I'm trying to combine two strings (strings/int) together with text in below code:
int foo = String((char*)payload).indexOf(' ');
int message1;
int message2;
message1 = String((char*)payload)....
-1
votes
1answer
32 views
Attempting to read random string from SD card
I was wondering if anyone knew how to read in a random string from a file named "PhraseList.csv" or "PhraseList.xlsx" (whatever is easier)? There is a list of 10k.
#include <SD.h>
#include <...
0
votes
1answer
24 views
Assign and control Digital pin from String
Here is modified version of Blink example
#define D8 13
String p = "D8";
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin ...
0
votes
0answers
28 views
How do I spilt a string of data into four different parts [closed]
The string has seconds, miles away from our point and latitude and longitude, and all we need is the lag and long
4271.645999999997,s,28.00301266666665,mi,28.48737418308778,N,-81.36210510944983,E. we ...
0
votes
0answers
17 views
append a String on ArduinoJson Object value
I've a json string request coming from server and I convert it into json object
StaticJsonBuffer<500> jsonStaticBuffer;
JsonObject& root = jsonStaticBuffer.parseObject(String(msg));
...
1
vote
2answers
31 views
Command through Serial monitor does not properly work in Arduino
I am executing a function in Arduino by giving String input to the serial monitor.
The issue here is when i enter "SHOW$" (without quotes) the function showData() works but when i enter the same "...
0
votes
0answers
29 views
How to store an array of doubles? As array of doubles, Strings or const char *? Then convert back to use?
This seems like an old, solved problem, but I can't find any simple answers.
I'm reading latitude and longitude data as Strings from a file (about 50 points), but they are really double float numbers.
...
0
votes
1answer
21 views
Help to delimit and read specific contents of incoming HTTP string
I am sending strings to an Esp8266 via web browser.
The below code returns the following in serial monitor if I send in browser:
Send from browser to esp8266 - http://192.168.1.220/s1s2s3s4s5d1
...
0
votes
2answers
48 views
String compare when using Serial
I try to detect commands given by user in Serial Monitor, but strcmp fails to flag as identical.
What do I do wrong ?
Is there a better way not reading as String and convert to char for comparison ?
...
3
votes
1answer
46 views
How to define and use a list/array of chars using `Serial.print` [closed]
I wish to define a list of months names and access it when printing a report.
Array was defined as follows:
const char months []=
{'Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov',...
-1
votes
0answers
43 views
Cannot encode any type of data using nanopb on Arduino
I am trying to encode some accelerometer data using nanopb, but this error pops up no matter which data type I try to encode:
no match for 'operator=' (operand types are 'pb_callback_t {aka ...
1
vote
1answer
52 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 ...
2
votes
2answers
121 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 ...
0
votes
3answers
62 views
Arduino IDE c++ 11 raw string literal have issues with // in http://, complier thinks // is comment
char webpage[] PROGMEM = R"=====(
<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/svg.js/2.6.6/svg.min.js"></script>
</head>
<body>
&...
7
votes
3answers
843 views
Why is 'n' parameter of snprintf ignored?
I have found that the n parameter of snprintf() seems to be ignored in my code.
char asdf[10];
Serial1.println(snprintf(asdf, 2, "hello"));
This prints 5 when I would expect it to print 2. What is ...
1
vote
2answers
34 views
ArduinoJSON: Using a reference to a reference when parsing array of arrays
I started to play around with the ArduinoJson library to parse data I got from one of my APIs (the format of the JSON data I get from my API can be improved for sure, but the software I had to ...
0
votes
3answers
124 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 ...
0
votes
1answer
623 views
Arduino Convert std:string to String
I'm working on BLE project with espressif library. And It returns me founded BLE device.
std::string getManufacturerData();
std::string getName();
int getRSSI();
BLEScan* getScan();
When ...
0
votes
1answer
41 views
Hex output although I always define integer
Code below is to read 4 thermometers and use values to turn on or off the heaters (I'm stuck at reading).
I'm reading and displaying temperature very well, but it comes to the problem, where I want ...
0
votes
2answers
152 views
Memory leakage caused by String Concatenation
In this link, section "Memory, memory, memory" it's been told that doing many String concatenations in sequence, e.g.: using operator+() multiple times, will cause memory fragmentation, which may lead ...
-1
votes
1answer
31 views
Passing out an argument
I can't figure out why test is not passed properly to test1
#include <Arduino.h>
char *test1;
char *status_reply(char *test) {
int ans_rel = 1;
int ans_led = 0;
int ...
1
vote
4answers
368 views
Local char* - keeps its value [closed]
Sorry for novice question in Arduino, but I'm trying to figure out why res is keeping its value when up_cmd0 is being called again.
for example - if num=8 in first run and the result is :up_cmd0_res: ...
1
vote
1answer
104 views
Return a char concatenation
My goal is to create a function that concatenate 2 chars into 1, and return it as MQTT subscribe. I get a difference between the results inside and outside the function ( I'm new to Arduino ), and I ...
1
vote
1answer
38 views
Doubt using character array
I'm trying to make a led sign with a WS2812b ledstrip, using the FastLed library (by the way, this is a great library!), I'm already able to show a text (so far only one, which I leave saved in an ...
0
votes
1answer
28 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(...
1
vote
2answers
138 views
Best practice to declare a 'static' text and save memory
I'm working on a project where I need to create a JSON to send back state of an object. I created the code to achieve it and all works fine, but I used this to declare the JSON fields:
static const ...
0
votes
1answer
17 views
Serial string readout analyzed and logged onto an SD card [closed]
I have a sensor that gives me this string, serially read @9600:
@T;+019.8;H;043.6;51
This burst arrives automatically about every second. It means:
"@" start of the string
"T;" means the ...
0
votes
0answers
57 views
How do I send a string after initiatint transmission in Arduino through SPI
I'm trying to send "hello\n" from master to slave but before I want to send qn initialization command like SPI.transfer(1)
Example master code.
#include <SPI.h>
void setup (void) {
...
0
votes
1answer
40 views
String input to character array
I am in between of project where i am getting string like "hello world" via Bluetooth to arduino I want to list this string into individual character so that I can call any of the character when ...
1
vote
2answers
50 views
Error handling strings and chars
I'm having an error in buffers that handle strings and I can not figure out what the problem is. The example below shows what is happening. Can someone help me?
void setup() {
char* ss1 = "";
...
0
votes
1answer
67 views
How do I clear previous values while using strcat() to add strings?
Is there any other function to add strings into buffer and updating values as well.
This is the problem I am coping with while using strcat()
char temp[2] = "A";
char temp_end[2] = "a";
char buf_adc[...
0
votes
2answers
107 views
How do i send ads1115 data over spi to master arduino
I am trying to send ADS 1115 data which is connected with Arduino mega_1 over I2C and arduino Mega_1 is connected with arduino Mega_0 over SPI.
Arduino Mega_1 is act as a slave and send ADS 1115 data ...
0
votes
2answers
468 views
Creating formatted String (including floats) in Arduino-compatible C++
I'm using a Mega2560 and a generic SSD1306 OLED display with the Adafruit_SSD1306 (and by extension, Adafruit_gfx) library.
I need to print a bunch of float values (ranging between 30.0 and 99.9) to ...
0
votes
1answer
37 views
String class summation disappears the right operand
I intend to create a function to jsify sensors' content and save it on a SD-card or send through a http client. Except for the Serial.println's, the function is transcripted below.
String jsonificar(...
0
votes
1answer
236 views
char array comparison
I'm having some issues dealing with strings in a small Arduino app.
I wonder why this code works:
mqtt.setServer("192.168.1.42", port);
and this code doesn't:
IPAddress ip = MDNS.queryHost(...);
...
0
votes
1answer
319 views
arduino nodejs serial data chunked and not in synch
I'm trying to get an arduino sending data to node but with no success.
I'm connecting to an ar-drone 2.0 as in https://gist.github.com/maxogden/4152815
Here is my Arduino code:
#include <...
2
votes
1answer
734 views
How to transmit string data using the rc-switch library?
I am using the rc-switch library for sending and receiving data. In rcswitch library, there is no method to send string data. I am using below method to send the string message in char buffer.
...
0
votes
1answer
323 views
Arduino HTTPClient passing string to variable
For some reason I can't seem to pass a simple string from one variable to another. Below is my code:
HTTPClient http; // Declare an object of class HTTPClient
http.begin(address); // Specify ...
0
votes
1answer
921 views
How do you convert a formatted print statement into a string variable?
I'm using the following routine to print the current time on the com port. I would like to capture this as a string so I can display it using ePaper.
void printLocalTime()
{
time_t rawtime;
...
0
votes
1answer
251 views
How do string pointers work in Arduino?
To the best of my understanding, when I declare
String s = "This is a string.";
what happens is that space is allocated on the stack for a pointer which points to some String object which internally ...
2
votes
1answer
207 views
Arduino String: use a non-null-terminated char array?
I'm using a library that takes a String as it's parameter (https://github.com/gmag11/painlessMesh)
I want to pass char arrays that is binary (UTF-8) data that also contains null-bytes (0x00). Right ...
1
vote
1answer
372 views
Save Leading Zero HEX into String RFID RC522 Arduino
I'm using RC522 to read RFID card. All is until if the HEX leading by 0 then i can't save it into String. But if i print it to Serial all is well. Here is my code:
#include <SPI.h>
#include <...
2
votes
2answers
270 views
How do I isolate numbers in text?
I need to separate numbers from the text where my string of numbers will always be of length 8:
string text = "77953505HELLO THIS IS A MESSAGE"; //my string of numbers will always be of length 8
My ...
0
votes
1answer
51 views
Can't assign String to Array of String
I have to input 5 words and organize.
In order to organize words, I have to get them into Array of String to compare.
I succeed to get char[buffer] into String in_str but somehow in_str doesn't
get ...
0
votes
1answer
306 views
string.indexOf() always returns a non-zero value
I am developing a hardware project which contains a facility to change the stored password by any user, if he/she knows the current password.The new password is stored in arduino eeprom. In the main ...
1
vote
1answer
228 views
Does the StringObject.reserve() function prevent memory fragmentation/leaks?
I'm currently writing and testing a professional Arduino application, I'm aware of the dangers of using the String class, so I began to implement C-style strings in some places, but it's just way ...
1
vote
2answers
1k views
function returning String-Array
i'm still new to arduino and also to C++ and have a short question.
What i want to do is to write a function (in my case to parse the query-string of an URL) to get the parameter names and values (...
1
vote
1answer
494 views
remove weird chars from char array ESP32
When I'm converting a string to a char array there are always some weird chars at the end.
I have to do it manualy because the convertTochar function crashes my ESP.
String sssid = module.getCssid()...
0
votes
2answers
302 views
Keypad password check issue
I am working on a school project, basically I have to create a lock system that opens a fictive gate when the correct code is entered. We have been asked to simulate our system before actually ...
0
votes
2answers
117 views
Why I get error on string concatination?
exit status 1
invalid operands of types 'const char [5]' and 'const char [2]' to binary 'operator+'
String message = "Page not found\n\n";
message += "URI: " + HTTP.uri() + "\n";
message += "...
