Comprehensive and Detailed Explanation From Exact Extract:
To determine the value of x when it is written to the debug log, we need to analyze the Apex code step by step, focusing on the behavior of the do-while loop and how it affects the variable x. Let's break down the code execution systematically, referencing Salesforce's official Apex Developer Guide.
Code Analysis:
The given Apex code is:
apex
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Integer x = 0;
do {
x++;
} while (x < 1);
System.debug(x);
Step 1: Initial State
* Integer x = 0;: The variable x is initialized to 0. The Apex Developer Guide states: "An Integer in Apex is a 32-bit number that does not include decimal points, initialized to 0 by default if no value is provided" (Salesforce Apex Developer Guide, Primitive Data Types). Here, x is explicitly set to 0.
Step 2: Understanding the do-while Loop
* A do-while loop in Apex executes the loop body at least once before evaluating the condition. The Apex Developer Guide explains: "The do-while loop executes the block of code in the do statement first, then checks the condition in the while statement. If the condition is true, the loop continues; otherwise, it exits" (Salesforce Apex Developer Guide, Loops).
* The loop body is:
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x++;
This increments x by 1 using the post-increment operator (++). The Apex Developer Guide confirms: "The ++ operator increments the value of the variable by 1" (Salesforce Apex Developer Guide, Expressions and Operators).
* The condition is:
apex
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while (x < 1);
The loop continues as long as x < 1 evaluates to true.
Step 3: Loop Execution
* First Iteration:
* Initial value: x = 0.
* Execute the loop body: x++ # x becomes 1 (0 + 1).
* Evaluate the condition: x < 1 # 1 < 1 # false (since 1 is not less than 1).
* Since the condition is false, the loop exits after the first iteration.
* After the Loop:
* The value of x is now 1.
* The do-while loop guarantees at least one execution, which is why x is incremented once before the condition check fails.
Step 4: Debug Statement
* System.debug(x);: This writes the value of x to the debug log. At this point, x = 1. The Apex Developer Guide states: "System.debug outputs the value of the specified variable to the debug log for troubleshooting" (Salesforce Apex Developer Guide, System Class).
* Therefore, the debug log will show 1.
Evaluating the Options:
* A. 0: Incorrect. The initial value of x is 0, but the do-while loop increments x to 1 in the first iteration, and the loop exits because the condition x < 1 is false. The debug log shows the final value of x, which is 1.
* B. 2: Incorrect. The loop only runs once because after the first iteration, x becomes 1, and the condition x < 1 fails (1 < 1 is false). There is no second iteration to increment x to 2.
* C. 1: Correct. As calculated, the loop executes once, incrementing x from 0 to 1, and then exits because the condition x < 1 is false. The debug log outputs x = 1.
* D. 3: Incorrect. The loop does not run enough times to increment x to 3. It only runs once, setting x to 1.
Why Option C is Correct:
Option C (1) is correct because:
* The do-while loop executes the body (x++) exactly once, incrementing x from 0 to 1.
* The condition x < 1 evaluates to false when x = 1, causing the loop to exit after the first iteration.
* The System.debug(x) statement outputs the final value of x, which is 1.
* This behavior aligns with Apex loop semantics as defined in the Salesforce Apex Developer Guide.
Handling Typos:
* The code in the image contains a typo: "salesforce" is randomly inserted in the middle of the do-while loop. This appears to be an artifact of the image and not part of the intended code. For analysis, we ignore this text and treat the code as:
apex
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Integer x = 0;
do {
x++;
} while (x < 1);
System.debug(x);
* There are no other syntactic issues in the code that affect the execution or outcome.
Example for Clarity:
To illustrate, here's how the code executes:
Integer x = 0; // x is 0
do {
x++; // First iteration: x becomes 1
} while (x < 1); // Condition: 1 < 1 # false, exit loop
System.debug(x); // Outputs: 1
If this code were run in a Salesforce org, the debug log would show:
DEBUG|1
References:
Salesforce Apex Developer Guide:
"Primitive Data Types" section: Defines the Integer type and its initialization.
"Loops" section: Explains the do-while loop's behavior, including guaranteed first execution.
"Expressions and Operators" section: Details the ++ increment operator.
"System Class" section: Describes System.debug for logging variable values.(Available at: https://developer.
salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/)
Platform Developer I Study Guide:
Section on "Developer Fundamentals": Covers Apex basics, including variables, loops, and debugging techniques.(Available at: https://trailhead.salesforce.com/en/content/learn/modules/platform-developer-i- certification-study-guide)