for
Loops through a block of PSL code for a specified period.
Syntax
{ BLOCK}
}
Parameters
Parameter | Definition |
|---|---|
initexpr | PSL statement whose evaluation initializes the loop |
termexpr | PSL relational expression whose evaluation determines the |
reinitexpr | PSL statement whose evaluation reinitializes the loop |
BLOCK | one or more PSL statements that are executed once in |
Description
The for loop behaves similarly to the C for loop construct in that it is an iteration statement in which the following occurs:
- The first expression initexpr is evaluated once, initializing the loop.
- The second expression termexpr is evaluated before each iteration and, if it becomes equal to 0, the for loop terminates.
- The third expression reinitexpr is evaluated after each iteration, reinitializing the loop.
The for loop is equivalent to the following example:
while (termexpr) {
BLOCK
reinitexpr;
}
Generally, initexpr and reinitexpr are assignments or function calls, and termexpr is a relational expression. Any of the three expressions may be omitted; however, the semicolons must remain. A missing second expression termexpr makes the implied test equivalent to testing a non-zero constant (or a permanently true expression).
The following example demonstrates the for loop:
printf(" %d seconds to go\n",i);
sleep(1);
}
The output of this example is as follows:
9 seconds to go
8 seconds to go
7 seconds to go
6 seconds to go
5 seconds to go
4 seconds to go
3 seconds to go
2 seconds to go
1 seconds to go
Where to go from here