Get a specific item from comma separated text

Question

I use bluetooth (works like serial monitor). Let me say i send a text to my hc-05 (same as sending to serial monitor) My current code is displaying text from serial monitor/HC-05 TO LCD

#include <LiquidCrystal.h>
LiquidCrystal lcd(4, 6, 10, 11, 12, 13);
String readString;
void setup() {
 Serial.begin(9600);
 lcd.begin(16, 2);
}
void loop() {
 while(Serial.available()){
 delay(50);
 char c=Serial.read();
 readString+=c;
 }
 if(readString.length()>0){
 Serial.println(readString);
 lcd.clear();
 lcd.print(readString);
 readString="";
 }
}

from serial monitor i type `a,b,c,d`

now my goal is to just get the a and display in lcd

or

in other words i want to get the value of a b c d in the text that is CSV to list or array and get value for index 1,2,3,4

OR

split string by delimiter

so how can i do it

details-ARUINO UNO

Answer 1

Use the strtok function.

From Geeks for geeks (https://www.geeksforgeeks.org/strtok-strtok_r-functions-c-examples/):

arguments:

• str: The string which is to be split
• delim: The character on the basis of which the split will be done Return value

The function performs one split and returns a pointer to the token split up. A null pointer is returned if the string cannot be split.

• Majenko: Note that to use strtok() you would first have to migrate away from using String, which is a good thing in any case.
• redoc: but the example is for c++ can you provide the example for Arduino
• Michel Keijzers: @hifitech Even though the Arduino/C++ string can be used, it's not a good idea because of the very low SRAM the Arduino Uno has. I assume with a default function and plenty of examples to be found on internet of using strtok it would not be a big problem to find a solution.

Answer 2

i searched in stack exchange Arduino but i dint get answer so i posted but when i searched in stack over flow i got link this is my final code

String part01;
String getValue(String data, char separator, int index)
{
 int found = 0;
 int strIndex[] = {0, -1};
 int maxIndex = data.length()-1;
 for(int i=0; i<=maxIndex && found<=index; i++){
 if(data.charAt(i)==separator || i==maxIndex){
 found++;
 strIndex[0] = strIndex[1]+1;
 strIndex[1] = (i == maxIndex) ? i+1 : i;
 }
 }
 return found>index ? data.substring(strIndex[0], strIndex[1]) : "";
}
void setup()
{
 Serial.begin(9600);
}
void loop()
{
 String part01 = getValue("523;524;525",';',1);
 Serial.println(part01);
}