Switch Statement Alternative

Question

I am working on a project where I've mapped an IR remote control to certain functions. I am currently using a massive switch statement to control the program based on the IR remote button pressed.

Is there a an alternative to using a switch statement, or is a switch the best way to go?

decode_results results; // Initialize the results

IRrecv irrecv(irPin); // Initialize the IR sensor


int buttonPressed;

void setup()
{
  Serial.begin(115200);
  Serial.println("Tile Controller");
  analogReference(DEFAULT);
  irrecv.enableIRIn(); // Start the receiver

  Wire.begin(); // Join the I2C network
}

void loop()
{  
  if (irrecv.decode(&results))
  {
    if(results.value != buttonHeld)
    {
      buttonPressed = results.value;
      Serial.println(buttonPressed,HEX);
    } 

    switch(buttonPressed)
    {
      case 0x3AC5: // 11 - Brightness Up
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Brightness Up Held");
          brightnessUpHeld();
        }
        else 
        {
          Serial.println("Brightness Up Pressed");
          brightnessUpPressed();
        }
        break;
      }

      case 0xFFFFBA45: // 12 - Brightness Down
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Brightness Down Held");    
          brightnessDownHeld();      
        }
        else 
        {
          Serial.println("Brightness Down Pressed");
          brightnessDownPressed();
        }
        break;
      }

      case 0xFFFF827D: // 13 - Pause
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Pause Held");
          pauseHeld();
        }
        else 
        {
          Serial.println("Pause Pressed");
          pausePressed();
        }
        break;
      }

      case 0x2FD: // 14 - Power
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Power Held");
          powerHeld();
        }
        else 
        {
          Serial.println("Pause Pressed");
          powerPressed();
        }
        break;
      }

      case 0x1AE5: // 21 - Red
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red Held");
          redHeld();
        }
        else 
        {
          Serial.println("Red Pressed");
          redPressed();
        }
        break;
      }

      case 0xFFFF9A65: // 22 - Green
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green Held");
          greenHeld();
        }
        else 
        {
          Serial.println("Green Pressed");
          greenPressed();
        }
        break;
      }

      case 0xFFFFA25D: // 23 - Blue
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue Held");
          blueHeld();
        }
        else 
        {
          Serial.println("Blue Pressed");
          bluePressed();
        }
        break;
      }

      case 0x22DD: // 24 - White
      {
        if(results.value == buttonHeld)
        {
          Serial.println("White Held");
          whiteHeld();
        }
        else 
        {
          Serial.println("White Pressed");
          whitePressed();
        }
        break;
      }

      case 0x2AD5: // 31 - Red 1
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red One Held");
          redOneHeld();
        }
        else 
        {
          Serial.println("Red One Pressed");
          redOnePressed();
        }
        break;
      }

      case 0xFFFFAA55: // 32 - Green 1
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green One Held");
          greenOneHeld();
        }
        else 
        {
          Serial.println("Green One Pressed");
          greenOnePressed();
        }
        break;
      }

      case 0xFFFF926D: // 33 - Blue 1
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue One Held");
          blueOneHeld();
        }
        else 
        {
          Serial.println("Blue One Pressed");
          blueOnePressed();
        }
        break;
      }

      case 0x12ED: // 34 - White 1
      {
        if(results.value == buttonHeld)
        {
          Serial.println("White One Held");
          whiteOneHeld();
        }
        else 
        {
          Serial.println("White One Pressed");
          whiteOnePressed();
        }
      }

      case 0xAF5: // 41 - Red 2
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red 2 Held");
          redTwoHeld();
        }
        else 
        {
          Serial.println("Red 2 Pressed");
          redTwoPressed();
        }
        break;
      }

      case 0xFFFF8A75: // 42 - Green 2
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green 2 Held");
          greenTwoHeld();
        }
        else 
        {
          Serial.println("Green 2 Pressed");
          greenTwoPressed();
        }
        break;
      }

      case 0xFFFFB24D: // 43 - Blue 2
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue 2 Held");
          blueTwoHeld();
        }
        else 
        {
          Serial.println("Blue 2 Pressed");
          blueTwoPressed();
        }
        break;
      }

      case 0x32CD: // 44 - White 2
      {
        if(results.value == buttonHeld)
        {
          Serial.println("White 2 Held");
          whiteTwoHeld();
        }
        else 
        {
          Serial.println("White 2 Pressed");
          whiteTwoPressed();
        }
        break;
      }

      case 0x38C7: // 51 - Red 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red 3 Held");
          redThreeHeld();
        }
        else 
        {
          Serial.println("Red 3 Pressed");
          redThreePressed();
        }
        break;
      }

      case 0xFFFFB847: // 52 -  Green 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green 3 Held");
          greenThreeHeld();
        }
        else 
        {
          Serial.println("Green 3 Pressed");
          greenThreePressed();
        }
        break;
      }

      case 0x7887: // 53 - Blue 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue 3 Held");
          blueThreeHeld();
        }
        else 
        {
          Serial.println("Blue 3 Pressed");
          blueThreePressed();
        }
        break;
      }

      case 0xFFFFF807: // 54 - White 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("White 3 Held");
          whiteThreeHeld();
        }
        else 
        {
          Serial.println("White 3 Pressed");
          whiteThreePressed();
        }
        break;
      }

      case 0x18E7: // 61 - Red 4
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red 4 Held");
          redFourHeld();
        }
        else 
        {
          Serial.println("Red 4 Pressed");
          redFourPressed();
        }
        break;
      }

      case 0xFFFF9867: // 62 - Green 4
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green 4 Held");
          greenFourHeld();
        }
        else 
        {
          Serial.println("Green 4 Pressed");
          greenFourPressed();
        }
        break;
      }

      case 0x58A7: // 63 - Blue 4
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue 4 Held");
          blueFourHeld();
        }
        else 
        {
          Serial.println("Blue 4 Pressed");
          blueFourPressed();
        }
        break;
      }

      case 0xFFFFD827: // 64 - White 4
      {
        if(results.value == buttonHeld)
        {
          Serial.println("White 4 Held");
          whiteFourHeld();
        }
        else 
        {
          Serial.println("White 4 Pressed");
          whiteFourPressed();
        }
        break;
      }

      case 0x28D7: // 71 - Red DIY Up
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red DIY Up Held");
          redDIYUpHeld();
        }
        else 
        {
          Serial.println("Red DIY Up Pressed");
          redDIYUpPressed();
        }
        break;
      }

      case 0xFFFFA857: // 72 - Green DIY Up
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green DIY Up Held");
          greenDIYUpHeld();
        }
        else 
        {
          Serial.println("Green DIY Up Pressed");
          greenDIYUpPressed();
        }
        break;
      }

      case 0x6897: // 73 - Blue DIY Up
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue DIY Up Held");
          blueDIYUpHeld();
        }
        else 
        {
          Serial.println("Blue DIY Up Pressed");
          blueDIYUpPressed();
        }
        break;
      }

      case 0xFFFFE817: // 74 - Quick
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Quick Held");
          quickHeld();
        }
        else 
        {
          Serial.println("Quick Pressed");
          quickPressed();
        }
        break;
      }

      case 0x8F7: // 81 - Red DIY Down
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Red DIY Down Held");
          redDIYDownHeld();
        }
        else 
        {
          Serial.println("Red DIY Down Pressed");
          redDIYDownPressed();
        }
        break;
      }

      case 0xFFFF8877: // 72 - Green DIY Down
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Green DIY Down Held");
          greenDIYDownHeld();
        }
        else 
        {
          Serial.println("Green DIY Down Pressed");
          greenDIYDownPressed();
        }
        break;
      }

      case 0x48B7: // 73 - Blue DIY Down
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Blue DIY Down Held");
          blueDIYDownHeld();
        }
        else 
        {
          Serial.println("Blue DIY Down Pressed");
          blueDIYDownPressed();
        }
        break;
      }

      case 0xFFFFC837: // 84 - Slow
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Slow Held");
          slowHeld();
        }
        else 
        {
          Serial.println("Slow Pressed");
          slowPressed();
        }
        break;
      }

      case 0x30CF: // 84 - DIY 1
      {
        if(results.value == buttonHeld)
        {
          Serial.println("DIY 1 Held");
          diyOneHeld();
        }
        else 
        {
          Serial.println("DIY 1 Pressed");
          diyOnePressed();
        }
        break;
      }

      case 0xFFFFB04F: // 84 - DIY 2
      {
        if(results.value == buttonHeld)
        {
          Serial.println("DIY 2 Held");
          diyTwoHeld();
        }
        else 
        {
          Serial.println("DIY 2 Pressed");
          diyTwoPressed();
        }
        break;
      }

      case 0x708F: // 84 - DIY 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("DIY 3 Held");
          diyThreeHeld();
        }
        else 
        {
          Serial.println("DIY 3 Pressed");
          diyThreePressed();
        }
        break;
      }

      case 0x708F: // 84 - DIY 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("DIY 3 Held");
          diyThreeHeld();
        }
        else 
        {
          Serial.println("DIY 3 Pressed");
          diyThreePressed();
        }
        break;
      }

      case 0xFFFFF00F: // 84 - DIY 3
      {
        if(results.value == buttonHeld)
        {
          Serial.println("Auto Held");
          autoHeld();
        }
        else 
        {
          Serial.println("Auto Pressed");
          autoPressed();
        }
        break;
      }

    }
    irrecv.resume(); // Receive the next IR value
  }
}

Can we have a glimpse at the portion of your code in question? This helps us to better understand how the decisions in your program are made and will lead to better answers. — Kwasmich
– Kwasmich, Commented Apr 18, 2017 at 9:54
You could have an array of structs, with each struct containing the key code, a name, a "pressed" function pointer and a "held" function pointer. — Mark Smith
– Mark Smith, Commented Apr 18, 2017 at 10:02
The array of structs sounds like a good idea. I've never used a function pointer before so I guess I've got some learning to do :) — Matt
– Matt, Commented Apr 18, 2017 at 10:09

Majenko · Accepted Answer · 2017-04-18 10:48:50Z

Your switch statement isn't that big - I've seen bigger.

However, as @MarkSmith says, using an array of structs with key codes and function pointers would be a way to go. For instance, you may have the struct:

struct button {
    uint32_t keycode;
    void (*press)();
    void (*hold)();
};

Populated with data it would look like:

const struct button buttons[] = {
    { 0x3AC5, brightnessUpPressed, brightnessUpHeld },
    { 0xFFFFBA45, brightnessDownPressed, brightnessDownHeld },
    ... etc ...
    { 0xFFFFF00F, autoPressed, autoHeld },
    { 0, 0, 0 }
};

Note the last entry of { 0, 0, 0 } - this is being used as an "end of list" marker. An alternative is to keep track of how many entries are in the list, but this makes adding / removing entries easier.

Then you can iterate through the list until you find a keycode that matches or the special keycode 0:

for (int i = 0; buttons[i].keycode != 0; i++) {
    if (buttons[i].keycode == buttonPressed) {
        if (results.value == buttonHeld) {
            buttons[i].held();
        } else {
            buttons[i].press();
        }
        break; // We found the button, no need to continue
    }
}

This method decreases the amount of code you have, but has the adverse effect of increasing the amount of RAM you use. It's a tradeoff between making the code simpler and using more RAM. If you can afford the RAM usage it can make things so much easier to read, since you have a simple table for the commands and a simple loop for finding the right entry in the table.

Wow, thanks for that reply & code examples. I'm definitely going to give it a try. — Matt
– Matt, Commented Apr 18, 2017 at 10:56

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