Arduino: if-compare parameters

Question

I'm trying to get a small BMP085 barometer project up and running. I want to be able to switch between different modes of operation (MODE_PRESSURE and MODE_ALT). I have MODE_PRESSURE and MODE_ALT defined as const int.

const int MODE_PRESSURE = 1;  // display pressure and temp
const int MODE_ALT      = 2;  // display altitude relative to sea level
int mode;                     // stores the current mode

void setup {
    mode = MODE_PRESSURE;
}

void loop {

    // Read mode button and set mode accordingly
    int buttonPressed = readButtons();

    switch(buttonPressed) {
    case BTN_MODE:
        if(mode == MODE_PRESSURE) { mode = MODE_ALT; }
        if(mode == MODE_ALT) { mode = MODE_PRESSURE; }
        Serial.println(mode); // <<-- always prints 1 ?!
        break;
    }
}

When the mode button is pressed, I want to toggle the current mode. But I'm stuck at if(mode == MODE_PRESSURE). This statement somehow never evaluates to true...?

I'm not very fluent in C, is there something I am missing? Can I not compare const int and int variables?

P.S.: I've also tried #define for MODE_PRESSURE and MODE_ALT, and const byte, but nothing seems to work.

Answer 1

Add else as follows:

    if(mode == MODE_PRESSURE)  
       mode = MODE_ALT; 
    else if(mode == MODE_ALT) # although not need but keep if here also
       mode = MODE_PRESSURE; 

You could also use nested-switch:

switch(mode){
     case MODE_PRESSURE: mode = MODE_ALT; 
             break; 

     case MODE_ALT: mode = MODE_PRESSURE; 
             break;
}