undesrstanding i++

in code leds trigger , dont seem go 1 @ time

code: [select]



byte red[] = {5, 9, 13, 22};
int ledstate = high;
long previousmillis = 0;        // store last time led updated

// follow variables long because time, measured in miliseconds,
// become bigger number can stored in int.
long interval = 250;

void setup() {
 // set digital pin output:

for (int i=0; i<sizeof(red); i++) {
       pinmode(red[i], output);  
}
}

void loop()
{
 // check see if it's time blink led; is, if
 // difference between current time , last time blinked
 // led bigger interval @ want
 // blink led.
 unsigned long currentmillis = millis();

 if(currentmillis - previousmillis > interval) {
   // save last time blinked led
   previousmillis = currentmillis;  
   // if led off turn on , vice-versa:
if (ledstate == low) (ledstate = high);
else (ledstate = low);
 for (int i=0; i<sizeof(red); i++)
   digitalwrite(red[i], ledstate);
 }

}



go easy im new this.

all want 1 led @ time...once again head hurts

i++ means take value of i, add 1 it, , save i. or, more simply, increases 1.

code: [select]

for (int i=0; i<sizeof(red); i++) {
        pinmode(red[i], output); 
}


sets of relevant pins outputs (which good). similarly,

code: [select]

for (int i=0; i<sizeof(red); i++)
    digitalwrite(red[i], ledstate);
  }

sets of relevant pins ledstate. they'll same value. when want each 1 change?

random comments:
you shouldn't sizeof(red), since if make red array of ints, return number twice big you're expecting. common way sizeof(red)/sizeof(red[0].
previousmillis , interval should both of type unsigned long, since that's millis() returns.
try indent better. each { should have indent on following line, , each } should have 1 less indent. makes easier see if matches code , such.

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