Needed a single loop capable of looping from 0 - 255 and 255 to 0 for a LED fading function. If the type is "up" then i want it to go from 0 to 255, if the direction is down then i want it to go from 255 to 0. One loop, two directions no repeated code.

gistfile1.cpp

//better soltion
void fade(char type[], int pins[],){
    //step though brightness in 255 steps, going up or down
    for (int i = 0; i < 255; i++ ) {
         int intensity = i; 
         if (type == "down") intensity = 255 - i;
         
         //loop for each group of LEDs
         for (int thisPin = 0; thisPin < 3; thisPin++) {
            analogWrite(pins[thisPin], intensity); 
          }
    }
}

//First solution
void fade(char type[], int pins[],){
    //step though brightness in 255 steps, going up or down
    if (type == "up") { 
    for (int i = 0; i < 255; i++ ) {
         //loop through each LED in group
         for (int thisPin = 0; thisPin < 3; thisPin++) {
            analogWrite(pins[thisPin], i); 
          }
    }
    } else {
    for (int i = 255; i > 0; i-- ) {
         //loop through each LED in group
         for (int thisPin = 0; thisPin < 3; thisPin++) {
            analogWrite(pins[thisPin], i); 
          }
    }

    }
}