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:
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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).
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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 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);
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), , , ]
