Question

Consider the following functions: int secret (int x) \\{\\[\begin{array}{l}\text { int i }, \quad j ; \\\i=2 * x ; \\\\\text { if }(i>10) \\\\\quad j=x / 2 ;\end{array}\\] else \\[\begin{array}{r}j=x / 3 \\\\\text { return } j-1\end{array}\\]\\}int another (int a, int b) \\{\\[\begin{array}{l}\text { int } i, \quad j ; \\\j=0 ; \\\\\text { for } \quad(i=a ; \quad i<=b ; \quad i++) \\\\\quad j=j+i ;\end{array}\\]return \(j;\)\\[\\}\\]} What is the output of each of the following program segments? Assume that \(x, y,\) and \(k\) are int variables. a. \(\quad x=10\) cout \(<<\) secret \((x)<<\) endl b. \(\quad x=5 ; \quad y=8\) cout \(<<\) another \((x, y)<<\) endl c. \(\quad x=10 ; k=\operatorname{secret}(x)\) cout \(<

Short answer

4, 26, "10 (4) 0", 0.

Step-by-step solution

Understanding the 'secret' Function

The "secret" function computes a value based on the input \( x \). It first doubles \( x \) and stores it in \( i \). If \( i > 10 \), it assigns half of \( x \) to \( j \). Otherwise, it assigns a third of \( x \) to \( j \). The function then returns \( j - 1 \).

Evaluating 'secret(10)'

First, calculate \( i = 2 \times 10 = 20 \). Since \( 20 > 10 \), compute \( j = 10 / 2 = 5 \). Finally, return \( j - 1 = 5 - 1 = 4 \).

Understanding the 'another' Function

The "another" function sums all integers from \( a \) to \( b \) inclusive and returns this sum. It initializes \( j \) to 0 and, in a loop, adds each integer from \( a \) to \( b \) to \( j \).

Evaluating 'another(5, 8)'

The loop iterates over 5, 6, 7, and 8. Calculating the sum: \( j = 0 + 5 + 6 + 7 + 8 = 26 \). The function returns \( 26 \).

Analyzing the Third Segment: 'x = 10; k = secret(x)'

Using the result from Step 2, \( k = 4 \). Next, 'another(10, 4)' is calculated, which results in 0 since \( 10 \) is not less than or equal \( 4 \). The output is "10 (4) 0".

Analyzing the Fourth Segment: 'another(8, 5)'

The function 'another' is called with 8 and 5, but the starting point 8 is greater than the end point 5. Therefore, the loop does not execute, and the result is \( j = 0 \).

Key concepts

Function Behavior

In C++, functions are like small programs you create within a larger program. They allow you to reuse code and make complex tasks simpler. When analyzing a function's behavior, it's important to understand its input, process, and output.

For instance, look at the `secret` function in our exercise. It takes an integer input, doubles it, and depending on the result, either halves the input or divides it by three. It then subtracts one from the result to produce the output. Recognizing these patterns helps in predicting what a function does without executing it.

Once you understand the behavior of a function, you can confidently predict what will happen when you use it with different inputs, thus writing better and more efficient code.

Control Structures

Control structures are crucial in managing the flow of a program. They allow you to dictate how certain parts of your code behave under various conditions. Key control structures include loops and conditional statements.

Consider the `secret` function. It uses an `if-else` statement. This control structure checks if a condition, like `i > 10`, is true. If it is, the program executes one block of code; if not, it executes another. This allows the function to decide dynamically what steps to take, offering flexibility and efficiency.

By mastering control structures, you can create programs that adapt to varying inputs and conditions.

Loops

Loops are a powerful mechanism in C++ programming that let you repeat a set of instructions until a certain condition is met. They simplify repetitive tasks.

For example, the `another` function uses a `for` loop to sum integers from `a` to `b`. The loop starts with `i` equal to `a`, continues to run as long as `i` is less than or equal to `b`, and increments `i` with each iteration. Instead of manually adding each number, the loop handles that automatically.

Understanding how loops operate can help you optimize tasks that involve repetitions, enabling you to write clean and concise code.

Integer Operations

Integer operations are basic math operations performed on integers, which are whole numbers without fractional components. They form the backbone of several computations in programming.

In the `secret` function, integer division is used when calculating values of `j`. For example, dividing 10 by 2 results in 5. Another example is dividing by 3, which might not be a whole number after division, but in integer operations, the result is floored. So, 5 divided by 3 gives 1.

Integer operations are fast and efficient and are mostly used for counting and indexing, crucial for loops and iteration in programming. Understanding how integer operations work ensures your programs handle data efficiently.