The dowhile loop is a control structure in Tipcontrol and slightly different to languages, such as C++,it is used to execute a block of code at least once and then repeat the execution as long as a specified condition evaluates to true. This structure guarantees at least one iteration, as the condition is checked after the loop body is executed. The difference to C an similiar languages is that the condition is written at the top of the control block dowhile(…) instead of after, even though the test is done after the execution.
Structure of a do...while Loop
Components:
- Condition: An expression evaluated aafter each iteration of the loop. If the condition evaluates to
true(non-zero), the code block inside the loop is executed again. If it evaluates tofalse(zero), the loop terminates. - Code Block: The block of code that executes during each iteration while the condition is true. This block is enclosed in curly braces
{}.
Simple Example
counter = 1; // Initialization
// Loop while counter is less than or equal to 5
dowhile (counter < 1) {
lib.log(“Count: “+ counter);
counter+=1; // Update the counter
}
Explanation:
- Initialization:
counter = 1;initializes a counter variable. - Condition:
counter < 1checks if the counter is less than or equal to 1, the loop in the example will run once as the condition is only checked after the code block. - Code Block: The statement
lib.log(“Count: “ + counter);is executed at least once, and then as long as the condition is true. - Update:
counter+= 1increments the counter at the end of each iteration to eventually make the condition false and terminate the loop.
Practical Use
The dowhile loop is particularly useful when you need a loop to execute the code block at least once, regardless of whether the condition is initially true or false, for example reading values from a sensor or other operations that need an initial value.