fileformatconverters Several variations of for loop statements in PHP

The for statement can be said to be the most basic statement in the loop control part of PHP (and in many languages). The execution rules and basic usage of the for statement will not be discussed here. You can refer to the for statement section of the PHP manual. Its syntax is defined in the PHP manual as follows:
for (expr1; expr2; expr3)
statement
　 Let’s talk about several useful variations of the for statement.
1. Infinite Loop
The first is the infinite loop (also called "dead loop") that everyone knows. Since the empty expression null is syntactically valid, we can leave the three expressions of the for statement empty, which will have the effect of continuously executing nested for statements.
for (;) Most programming tasks, especially those involving PHP, will add some conditions to terminate the loop when using infinite loops.

for (;;) {
//If it is 2199 AD, break out of the loop
if (

date
('Y'
) ==
'2199') {                                                                            break A common function is to complete more complex initialization work. if (isset($i)) { unset(
$i

);
if ((int) date
(

''
) <
2008) {                                                                 =
1; }
} else { $i =3;}for (;
$i < 10;$i

++) { echo $i ;}
?>

In the same way, the iteration expression expr3 may also be left blank. You can also use this to write more complex iterations, such as calling different iterations according to different conditions. 　Leaving the conditional statement expr2 in the for statement blank is the infinite loop mentioned above. Of course, you can also add some more complex conditions to determine when to jump out of the loop, which will not be repeated here. 3. Multiple loopsUsing multiple loops to control multiple variables is also a feature that is often overlooked in the for statement. As in the example below, double loops are generally used in general tasks, and loops of three or more are generally of little significance.
for ($i = 0, $j = 10;$i ) <= 10 ;$i++, $j--) {
 echo "$i + $j = 10rn";
}
?>

The above code Will output:
0 + 10 = 10
1 + 9 = 10
2 + 8 = 10
3 + 7 = 10
4 + 6 = 10
5 + 5 = 10
6 + 4 = 10
7 + 3 = 10
8 + 2 = 10
9 + 1 = 10
10 + 0 = 10
4. More complex expressions
If the three expressions of the for statement are written more complexly, they can be used to optimize the algorithm. You can even use a for statement without a loop body to complete some tasks. For example, calculate the accumulation or factorial:
//Calculate the accumulation result of 1-5, and the value is $j
for ($i = 1, $j = 0; $i <= 5;$j += $i++);
e cho $j ;
//Calculate the factorial result of 1-5, the value is equal to $j
for ($i = 1,$j = 1 ; $i <= 5;$j *= $i++);
echo $j;
?>

　 PHP uses the syntax of C language and will also have the characteristics of C to a certain extent. For example, the powerful for loop statement is a typical example.

The above introduces several variations of the for loop statement in fileformatconverters PHP, including the content of fileformatconverters. I hope it will be helpful to friends who are interested in PHP tutorials.