Can a for Loop Be Written to Create an Infinite Loop or Is It Only While Loops That Do That?
Can a for Loop Be Written in Java to Create an Infinite Loop or Is It Only While Loops That Cause That Problem? 3 12 Answers For(; ;){} Is Same as...
Can a for loop be written in Java to create an infinite loop or is it only while loops that cause that problem?
12 Answers
for(;;){}
is same as
while(true){}
You can also do such with for loops. E.g. the following is identical to while(true):
for(;;) {
}
Apart from issues of scope and one other thing, this:
for(<init>; <test>; <step>) {
<body>
}
is the same as:
<init>
while(<test>) {
<body>
<step>
}
As other people have alluded to, in the same way that you can have a while loop without an <init> form or <step> form, you can have a for loop without them:
while(<test>) {
<body>
}
is the same as
for(;<test>;) {
<body>
} //Although this is terrible style
And finally, you could have a
for(;true;) {
<body>
}
Now, remember when I said there was one other thing? It's that for loops don't need a test--yielding the solution everyone else has posted:
for(;;) {
<body>
}
Sure you can
for(int i = 0; i == i; i++) {}
Any loop can be made infinite as long as you make a way to never hit the exit conditions.
Dont forget mistakes like
for (int i=0; i<30; i++)
{
//code
i--;
}
It's not as uncommon as it should be.
Just for fun (and this too long for a comment): a lot of people will be very surprised to learn that for a lot of very practical purposes the following is nearly an infinite loop:
for (long i = Long.MIN_VALUE; i < Long.MAX_VALUE; i++) {
...
}
If the thread executing this loops can do 4 billions cycles per second and can do the increment and the check in one cycle (quite beefy for a single thread) and if my maths ain't totally off, I think the above code needs about 150 years to execute : )
I'll just add this since nobody did this version:
for(;;);
The way I made my server to run as long until I shut it down is
for(int i = 0;i<-1;i++){//code here}
Ofcourse for loops can cause infinite loops. An example is:
for(int i = 0; i < 99; i /= 2){ ... }
Because i is never incremented, it will stay in the body of the for loop forever until you quit the program.
There is also this one, to complete the topic:
do {something();} while(true);
There's lots of ways to make for loops infinite. This is the solution I found:
int j = 1;
for (int i = 0; i < j; i++) {
//insert code here
j++;
}
This works really well for me because it allows the loop to check an infinite amount of values as well as looping infinitely.
you can declare a subpart of the code to be another part in a for loop, example -
public class (classname) {
for(int i = 1; i <= 4; i++) {
for(int j = 1; i <= 4; j++) {
system.out.println(i + "*" + j + "=" (i*j));
}
}
it is almost in infinite loop; if you change int to long, and add more variables, you can practically make it last 25 x 10^12 minutes long
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