The Strings in Arduino They are very useful tools. you must use to program your board. Because of this, it is important to know what these functions are for and what are the classes of Strings that you can find
For this it is necessary that you read this article until the end because We will explain what are the Strings that exist and how is the syntax that you should use to understand his work.
But this is not all, you can also find a guide to correctly use a String (Object) and a list of the best projects you can do yourself to practice.
What is a String in Arduino programming and what are they for when programming this type of hardware?
In, Strings are tools used to store strings of characters. Therefore, it is not considered a String as a data in itself, but as a class dependent on them. The termination they have is by means of a null character. In addition, they are characterized by reserving a certain memory capacity of the to create a buffer and be able to use intensively the functions they offer to users.
Types of Strings in Arduino programming What are all the ones that exist?
can be found different types of Strings used in programming Arduino.
We will show you each of them below:
Char Array
Char Arrays are arrays of characters that are used in large strings of texts.. That is, every time you work on a string with a C++ language that ends in a value 0 (\0), consecutive memory structures are created, so they take up less memory and if you don’t would identify a String as char. Note that you always have to end with a null character and you can refer to individual characters in the string.
Object
In case of not working with large amounts of texts you can use a String Object. These classes of data improve the handling of character strings by means of methods which are used by users to compare two strings, find certain characters, concatenate, and add elements to the string, among other functions.
String Operators
Operators are symbols that are used to set a particular instruction to the String. In this way, actions can be established that serve to add, extract and see if a certain character in the string is true or not.
Syntax of a String (char array) How to understand its declarations and conditions of use?
When using a long text string you will have to use a Char Array.
To do this, we show you how you should handle it:
statements
The declarations that are valid in a string for a String are:
- char Str1; This syntax is used to initialize an array in a general way.
- char Str2 = {‘a’, ‘u’, ‘i’}; In this case additional characters are set, I want and compiler will add the null character.
- char Str3 = {‘a’, ‘u’, ‘i’, ‘\0’}; If you prefer and want to insert the null character manually, you’ll need to use this structure.
- char Str4 = “ipap”; You can initialize a string with a constant using single quotes. The IDE will set the size of the array.
- char Str5 = “ipaparduino”; If you set the size manually and indicate a constant, you must use this syntax.
- char Str6 = “ipaparduino”; This structure allows a larger string to be added, since a white space is left.
null termination
Null endings are used to define where a string endsfor this it is necessary to include a null characterof , at the end of the function. It can be included manually by writing “\0” or automatically, so that it has been .
string arrays
The matrices are used to configure strings that have large amounts of texts. In this way you can work more easily because the complexity of handling is reduced.
Learn step by step how to use a Strings (Object) to program in Arduino
To use a String in the IDE you must follow this step by step:
Syntax
The first thing you will have to to know is how to handle the structure that has a String.
To do this, you will have to take into account the syntax used in a String (Object):
- String(val)
- String(val, basis)
- String(val, decimalPlaces)
parameters
Then, you will have to implement the parameters, which are used in the above syntax:
- val: refers to the variable that needs to be formatted to get a string. The data supported in these parameters are byte, char, double, float, int, long, string, unsigned int, and unsigned long.
- base: this parameter is optional and shows the base in which the variable should be formatted. It defaults to base 10, but can also be used in hexadecimal and binary base. For example, String(14, HEX) and String(13, BIN).
- decimalPlaces: when a float or double data is used as values, the decimal place must be established.
functions
Finally, you will have to incorporate functions to the String.
The functions used in the Arduino IDE are:
- charAt(): this function is used to access a particular element of the string.
- compareTo(): With this tool you can compare two strings and thus establish if they are equal or not.
- concat(): when you need to add an element or parameter to the string you will have to use this function.
- c_str(): This variable is used when you need to convert a string to a C string.
- endsWith(): It is used to check if a certain string ends with a specific character.
- equals(): You can use this function to compare two strings and find equality.
- equalsIgnoreCase(): Like the previous function, this variable is used to compare two strings, but is case-insensitive.
- getBytes(): Allows you to copy characters from a string.
- index(): This function is used on a String when you need to search for a string or a value within a string.
- lastIndexOf(): is used to find a character or a string.
- length(): when I need to know the length of the string, you will have to use this function.
- remove(): removes or modifies characters.
- replace(): You can substitute one character for another within a string.
- reserve(): This function can be used to establish a buffer to the board’s memory and in this way manage to work with processes without affecting the performance of the hardware.
- setCharAt(): It is used to incorporate a character.
- starts with (): this anointing is characterized by checking if a string starts with a certain element.
- substring(): its name says it all, this function is used to get a substring within a string.
- toCharArray(): It allows copying characters within the buffer that is selected to have a space in memory.
- toDouble(): if the string is valid, it can be used to duplicate it.
- toInt(): a string can be converted to an integer, as long as the string is valid.
- toFloat(): manages to convert a String to a float character.
- toLowerCase(): When the String is written in uppercase and you need to change it to lowercase, you must use this function.
- toUpperCase(): is the inverse situation to the previous function.
- trim(): You can use this tool to get a white space at the beginning or end of the version of the String.
List of the best projects programmed with Strings that you can do yourself to practice
We will show you below the best projects that you can program yourself using Strings.
Let’s start:
quick response device
With a , a push button, a breadboard, a led screen, a 10k resistor set necessary for the installation you can create a screen in which you enter a question and receive a random answer. To incorporate the questions and answers should use the String.
The codes you should use:
#include
Now, you will have to include the variables and configure them on the screen display:
#define SCREEN_WIDTH 128 #define SCREEN_HEIGHT 32 #define STRING_ARRAYSIZE 10 // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins) – Arduino UNO: A4(SDA – Data ), A5(SCL – Clock) #define OLED_RESET 4 / / Reset pin # (or -1 if sharing Arduino reset pin) Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
Set the button variables:
const int buttonPin = 2; int buttonState = 0; int lastButtonState = 0; int randomNumber = 0; String mainText = “Ask”; void setup() { // Serial setup begin(9600); // OLED setup // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128×32 println(F(“SSD1306 allocation failed”)); for(;;); // Don’t proceed, loop forever } displayTextOnOLED(mainText); // PIN dedicated to button setup pinMode(buttonPin, INPUT); // if analog input pin 0 is unconnected, random analog // noise will cause the call to randomSeed() to generate // different seed numbers each time the sketch runs. // randomSeed() will then shuffle the random function. randomSeed(analogRead(0)); } // purpose is to listen to button state // and when pressed the OLED to display a different text // when released to show the setup() text void loop() { // read the state of the pushbutton value: buttonState = digitalRead(buttonPin); if ( buttonState != lastButtonState ){ if (buttonState == HIGH) { displayTextOnOLED(randomText()); } else { displayTextOnOLED(mainText); } } lastButtonState = buttonState; } void displayTextOnOLED(String str) { clearDisplay(); setTextSize(2); // Draw 2X-scale text setTextColor(SSD1306_WHITE); setCursor(0,0); println(str); display(); // Show initial text }
Use the string:
String randomText(void) { String texts = {“Da”, “Nu”, “Nu stiu!”, “Nu vreau!”, “Du-te naibii!”,”Varule”,”Te pup!”,”Sigur !”, “Sigur ca nu!”,”Nah!”}; if ( buttonState != lastButtonState ) { randomNumber = random(1, 10); return texts; } else { return texts; } }
radar station
You will need an Arduino board in this projectan ultrasonic sensor of the model HC-SR04, a servo motor, cables and a 10k resistor. You are going to have to connect the sensor to pins 10 and 11 of the board and then the servo to pin number 12.
Next, you will have to enter these codes using Strings:
#include
To control the servo motor you will have to create a servo object:
Servo myServo; void setup() { pinMode(trigPin, OUTPUT); output PinMode(echoPin, INPUT); begin(9600); attach(12); } void loop() {
Program the radius of rotation of the servomotor between 15 and 165 degrees:
for (int i = 15; i <= 165; i++) { write (i); delay(30); distance = computeDistance(); print(i); print(","); print(distance); print("."); } for (int i = 165; i > 15; i -) { write ( i ); delay(30); distance = computeDistance(); print(i); print…
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