Question

If the following pseudocode were an actual program, what would it display? Declare String s1 = "New York" Declare String s2 = "Boston" If s1 > s2 Then Display s2 Display s1 Else Display s1 Display s2 End If

Short answer

Answer: The final output will be: ``` New York Boston ```

Step-by-step solution

Understand the Pseudocode Declarations

First, two string variables are declared: s1 and s2. s1 is assigned the value "New York," and s2 is assigned the value "Boston."

Analyze the Pseudocode Conditions

The given pseudocode is comparing s1 with s2 using the '>' operator. Since the variables are strings, the comparison is performed lexicographically (comparing the characters' Unicode values). The pseudocode will display both strings based on their lexicographical order (ascending or descending) based on the given condition.

Compare the Strings

The '>' operator checks if s1 comes after s2 in lexicographical order. Here, "New York" comes after "Boston" in lexicographical order, so the condition (s1 > s2) is false.

Run the Code in the Else Condition

Since the given condition (s1 > s2) is false, the pseudocode will run the 'Else' part. According to the 'Else' part, first s1 ("New York") is displayed, followed by s2 ("Boston").

Determine the Final Output

Based on the pseudocode, when the condition (s1 > s2) is false, it displays "New York" (s1) first and then "Boston" (s2). Therefore, the final output will be: ``` New York Boston ```

Key concepts

Understanding Programming Logic in Pseudocode

Grasping the concept of programming logic is fundamental when interpreting pseudocode. Pseudocode is a simplified and readable version of programming code that outlines the logic without the syntactic rules of a specific language. Think of pseudocode as a recipe for a computer program; it lists the steps needed to reach the final dish—the result. But instead of culinary instructions, pseudocode consists of logical steps to solve a computing problem.
In the given exercise, the logic pertains to comparing two strings and displaying them based on a specified condition. The effectiveness of a programmer often relies on the clarity of thought and the ability to break down problems into manageable logical steps. Creating or reading pseudocode is an excellent way to achieve this, as it helps to visualize the flow of operations and understand the sequence in which they are executed before translating them into actual code.

Decoding String Lexicographical Order

Lexicographical order is a system often found in dictionaries or telephone directories. In computing, it's a method to determine the sequence of strings the way a dictionary would, based on the alphabetical order of their component characters. Each character is assigned a numerical value, typically based on the Unicode standard—a character encoding system.
To compare strings in lexicographical order, the programming logic considers these numerical values. It begins by comparing the first character from each string. If they differ, the string with the lower value (earlier in the alphabet) is considered 'less than' the other. If they are equal, the comparison moves on to the next character, and so on.
For instance, in our exercise, 'New York' and 'Boston' are compared. The comparison starts with 'N' from 'New York' and 'B' from 'Boston.' Since 'B' comes before 'N' in the alphabet, 'Boston' is considered less than 'New York' in lexicographical order. Students often find it helpful to imagine lining up words just as they would appear in a sorted list, to determine which comes first.

Leveraging Conditional Statements

Conditional statements are the decision-makers in programming. When writing code, we constantly need to perform actions based on conditions. An 'if-else' statement, such as the one in the pseudocode exercise, evaluates a condition and directs the flow of the program accordingly—if the condition is true, one block of code executes; if false, another block executes.
The '>' operator is a comparison tool that helps to set conditions for these statements, by checking if one value is greater than the other. As we saw in the pseudocode, when comparing strings, 'greater than' translates to 'comes after in lexicographical order.' It is crucial to understand that the lexicographical comparison is case-sensitive and whitespace can affect the outcome, which are both frequent sources of confusion for beginners.
Learning to construct and utilize conditional statements effectively is a cornerstone of programming logic. It requires a clear understanding of the significance of operators and the data that is being evaluated, like knowing that with strings, these operators compare order, not magnitude.