c++ - Sending multiple values through serial port -


i using arduino uno project, don't know how go achieving want. i'm beginner therefore don't know how use functions want.

i want send 3 values through serial monitor @ once.

the first value string points operator (a, s, m, d, p), , want take 2 more values. example, if input 'a012556 should add 12 , 556 give me 568.

currently doing this, it's asking each input separately. example, ask operator (i can input ints because cannot take string/chars) first, input 1 (should addition), , asks first number, , second number, , adds them both , outputs result. works fine, it's not i'm trying achieve. 

  serial.println ("enter chosen operator");   serial.println ("a addition, s subtraction, m multiplication,");   serial.println ("d division, , p potentiometer: ");    // takes input user   int theoperator = datainput();    if (theoperator == 1) {     // if input equal 1, carry out function 'addition()'     addition();   } else if ..............

above in loop function currently, , points function below. same subtract/multiply/divide/etc.

  void addition() {    serial.println ("a");   serial.println ("please enter first number in format nnn: ");   firstnumber = datainput(); // asks user input first set of numbers    /* message must in format cnnnnnn      therefore first number must greater or equal -99 , less or equal 999*/   if (firstnumber >= -99 && firstnumber <= 999) {     serial.println (firstnumber); // prints first set of numbers user view   }   else {     /* if data input not match format cnnnnnn error message display        if input invalid red led turn on */     digitalwrite(led_red, high);     serial.println ("--------------- error ---------------");   }    serial.println ("please enter second number in format nnn: ");   secondnumber = datainput(); // asks user input second set of numbers    /* message must in format cnnnnnn      therefore second number must greater or equal -99 , less or equal 999*/   if (secondnumber >= -99 && secondnumber <= 999) {     // led turn off if on because valid input     digitalwrite(led_red, low);     serial.println (secondnumber); // prints second set of numbers user view   }   else {     digitalwrite(led_red, high);     serial.println ("--------------- error ---------------");   }    /* give time red error led stay on      user notice he/she has made invalid input */   delay(500);   digitalwrite(led_red, low);    // case addition, add first , second numbers   value = (firstnumber + secondnumber);    serial.print("value: ");   // prints value of 2 sets of numbers user can see value of message   serial.println(value); }

therefore there way of doing this? need substring?

thank in advance, advice appreciated.

yes, substring need.

fortunately, string provides substring function.

https://www.arduino.cc/en/reference/stringsubstring

you code bit this:

// expecting operation in "oxxxyyy" o operator, xxx, yyy operands.     bool parseoperation(string& strinput, char& op, int& x, int& y)    {        if (strinput.length() != 7)            return false;         op = strinput[0];        x = atoi(strinput.substring(1, 4).c_str());        y = atoi(strinput.substring(4).c_str());        return true;    }     // call as:     void loop()    {        string str;        char op;        int r, x, y;         // read user input str...         if (parseoperation(str, op, x, y))        {            switch(op)            {            case 'a': case 'a':                 op = '+';                 r = x + y;                 break;             // etc...             default:                 // print error message...                 break;            }            // print x op y = r        }        else        {             // print error message...        }    }

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