Question 43

Declare variable Diff.

The first step of the algorithm is to declare the variable Diff. This step is essential as it sets up the variable that will be used to store the calculated difference later in the algorithm.

A) Set Diff = x - y.

This option is incorrect because it suggests a calculation that occurs after the variable has been declared. The declaration of the variable must precede any assignment or calculation involving it.

B) If y > x, set Diff = y - x.

This option is also incorrect as it describes a conditional step that occurs later in the algorithm. The declaration of the variable is a prerequisite for any subsequent operations, including conditions and calculations.

C) Declare variable Diff.

This option is correct as it represents the first and necessary step in the algorithm. Declaring the variable ensures that it exists and can be utilized in the steps that follow.

D) Put Diff to output.

This option is incorrect because it refers to an action that takes place after the variable has been calculated. Outputting the value of Diff cannot occur until it has been assigned a value through prior calculations.

Conclusion

Declaring the variable Diff is the foundational step in the algorithm, enabling all subsequent operations to reference and manipulate this variable. All other options describe actions or conditions that rely on the existence of Diff, making them invalid as the first step in the algorithm.