Why is this extremely simple code not working?

Question

I have a problem with a for loop, and Serial.print("Its Working") does not appear. Seems simple, I've done it before, now for whatever reason, its not working anymore

void setup() {
 // put your setup code here, to run once:
 Serial.begin(9600);
}
void loop() {
 // put your main code here, to run repeatedly:
 for (int x = 0; x > 10; x++) {
 Serial.println("Its Working");
 delay(1000);
 }
}

Answer 1

The problem is:

for (int x = 0; x > 10; x++) {

That can be rewritten, in pseudo code, as:

• X is zero
• While X is greater than 10:
  • Increment X

You see the problem? X is zero. It's not greater than 10, so it never increments.

I assume you actually wanted:

for (int x = 0; x < 10; x++) {

Also be aware that your for loop will be run over and over again, so you will never see it finish. You should add

Serial.println("Loop done");

at the end so you know it's finished.

• Coder9390: Essentially, the for loop never starts as the first time it checks the condition, its already false, right?
• Majenko: @Coder9390 That is correct.
• Peter Cordes: @Coder9390: You can see that for yourself by single-stepping your code with a debugger. You'll see execution skip over the loop without ever entering the loop body. That's your hint that you accidentally wrote a loop condition that's false on the first check. Remember that a for loop is basically the same as part1; / while(part2){ ...; part3; }, so like a while loop, the condition is checked before entering the loop for the first time.
• Peter Cordes: @Coder9390: Using a debugger is essential for low-level stuff where alternatives like sprinkling debug-print statements in your code aren't easy, or to help catch brain-farts where something you're assuming you got right was actually the problem.