PHP Increment by Half

问题

I have a quick question, which is probably easy to answer. I've goolged around, but not sure if I am searching correctly or what. Anyway, using PHP, how can I increment by halves?

For example, I know I can use the following loop:

<?php 
for ($i=1; $i<21; $i++) {
    print($i);
}

And it will print 1 - 20.

But, how can I get it to output something like the following:

1
1.5
2
2.5
etc...

Sorry for my ignorance on this, I'm just not sure how to go about it. Thanks!

回答1:

Change $i++ to $i += 0.5. Also, to print each number on its own line you need to use \n (or <br> if you're outputting HTML to a browser).

for ($i = 1; $i < 21; $i += 0.5) {
    print($i . "\n");
}

The above code will print 20.5 because it's less than 21. If you want to print a maximum of 20, change the loop condition to check $i <= 20 instead:

for ($i = 1; $i <= 20; $i += 0.5) {
    print($i . "\n");
}

回答2:

Just one more solution to choose from.

foreach (range(1, 20, 0.5) as $i) {
  // Do something with $i
}

回答3:

Loop to double the amount (adjust upper and lower bounds appropriately) and divide by two in the output.

E.g.

for ($i=2; $i<41; $i++) print($i/2);

to output from 1 to 20 in increments of .5

回答4:

instead of $i++, use $i += .5

回答5:

Here's something that could work.

$i += round(exp(log(2)/2) * 2) / 2 - ENT_QUOTES + IMAGETYPE_JPEG;

来源：https://stackoverflow.com/questions/4822611/php-increment-by-half