How to store numbers in Arduino? - c++

Question

I have written this to an Arduino.
char incomingbytea;
char incomingbyteb;
char incomingop;
char result;
void setup()
{
Serial.begin(9600);
}
void loop(){
incomingbytea = 0;
incomingbyteb = 0;
incomingop = 0;
result = 0;
bytea:
if (Serial.available() > 0) {
incomingbytea = Serial.read();
Serial.println("1ok");
Serial.println(incomingbytea);
goto byteb;
}
goto bytea;
byteb:
if (Serial.available() > 0) {
incomingbyteb = Serial.read();
Serial.println("2ok");
Serial.println(incomingbyteb);
goto op;
}
goto byteb;
op:
if (Serial.available() > 0) {
incomingop = Serial.read();
Serial.println("opok");
Serial.println(incomingop);
goto oper;
}
goto op;
oper:
result = incomingbytea + incomingbyteb;
Serial.println(result);
Serial.println(incomingbytea);
Serial.println(incomingbyteb);
Serial.println(incomingop);
}
What I want to do is:
- connect to serial (check)
- collect 2 variables to add/subtract/multiply/divide later (check)
- collect a variable to decide what to do with them 1-add, 2-subtract, etc. (check)
- redirect the script to do the required operation (later)
- print the result to serial (check)
The problem is, when I enter 1 and 1 and 1(whatever, the third one doesn't count now) and I get 98 as a result. Any help? Maybe the variables are wrong?

Answer 1

First you should know the length of the number, and subtract 48 (48 is the ascii representation of 0) later multiply the number for 1, 10, 100, 1000, 10000, ... depending of the position of each number.
For example: String "233" to integer, using custom method
void setup() {
Serial.begin(9600);
}
void loop() {
String Numero1 = "40";
String Numero2 = "50";
double Suma = StringAInt(Numero1)+StringAInt(Numero2);//+ StringAInt(Numero2);
Serial.println(Suma);
}
double StringAInt(String Dato)
{
String Numero = Dato;
char Valores [Numero.length()+1];
Numero.toCharArray(Valores,Numero.length()+1);
double NumeroEnt = 0;
for(int i = 0; i<Numero.length(); i++)
{
int NumValores = Valores[i];
NumValores-=48;
double MultPor = pow(10,Numero.length()-(i+1));
NumeroEnt += (NumValores*MultPor);
//Serial.println(NumValores*MultPor);
}
return NumeroEnt;
}
Now you only need build a string with the data received from serial port, and you can do math simply.