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copied!<p>Conditional expressions are used by the conditional and loop control structures to determine the control flow of a program.</p> <pre><code>// conditional control structure if (conditionalExpression) { codeThatRunsIfConditionalExpressionIsTrue(); } else { codeThatRunsIfConditionalExpressionIsFalse(); } // basic loop control structure while (conditionalExpression) { codeThatRunsUntilConditionalExpressionIsFalse(); } // run-at-least-once loop control structure do { codeThatRunsAtLeastOnceUntilConditionalExpressionIsFalse(); } while (conditionalExpression); </code></pre> <p>From a logical point of view, conditional expressions are inherently boolean (true or false). However, some languages like C and C++ allow you to use numerical expressions or even pointers as conditional expressions. When a non-boolean expression is used as a conditional expression, they are implicitly converted into comparisions with zero. For example, you could write:</p> <pre><code>if (numericalExpression) { // ... } </code></pre> <p>And it would mean this:</p> <pre><code>if (numericalExpression != 0) { // ... } </code></pre> <p>This allows for concise code, especially in pointer languages like C and C++, where testing for null pointers is quite common. However, making your code concise doesn't necessarily make it clearer. In high-level languages like C# or Java, using numerical expressions as conditional expressions is not allowed. If you want to test whether a reference to an object has been initialized, you must write:</p> <pre><code>if (myObject != null) /* (myObject) alone not allowed */ { // ... } </code></pre> <p>Likewise, if you want to test whether a numeric expression is zero, you must write:</p> <pre><code>if (numericalExpression != 0) /* (numericalExpression) alone not allowed */ { // ... } </code></pre>

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