Converting a char* with numbers to a double is giving me 0.0 in return

Question

I recently made a thread where I read BLE data that has three different numbers/values. The data changes but it typically looks something like this: 0,5 -0,1 0

I successfully store the three numbers in a unique char* but when I try to convert the char* to a double I get the value 0.0 in return.

This is my code:

        while (tok)
        {
            if (currentRow == 0)
            {
              currentRow = currentRow +1;
              double a = atof(tok);
              Serial.println (a);
            }

            else if (currentRow == 1)
            {
              currentRow = currentRow+1;
              double b = strtod(tok, NULL);
              Serial.println (b);
            }

            else {
              currentRow = 0;
              double c = atof (tok);
              Serial.println (c);
            }

            tok = strtok(NULL, " "); 
        }

Answer 1

The value that was being sent used a comma "," instead of a dot "." that was needed in order to convert the number.