Question

What is the output of the following statements? Suppose a and b are int variables, c is a double variable, and a = 13, b = 5, and c = 17.5. a. cout << a + b – c << endl; b. cout << 15 / 2 + c << endl; c. cout << a / static_cast(b) + 2 * c << endl; d. cout << 14 % 3 + 6.3 + b / a << endl; e. cout << static_cast(c) % 5 + a – b << endl; f. cout << 13.5 / 2 + 4.0 * 3.5 + 18 << endl;

Short answer

a: 0.5, b: 25.0, c: 37.6, d: 8.6846, e: 10, f: 38.75.

Step-by-step solution

Evaluate Expression a

The expression is: \[a + b - c = 13 + 5 - 17.5\]First, add \(a\) and \(b\):\[13 + 5 = 18\] Then, subtract \(c\):\[18 - 17.5 = 0.5\]So, the output of statement (a) is `0.5`.

Evaluate Expression b

The expression is:\[15 / 2 + c = 15 / 2 + 17.5\]First, perform the division:\[15 / 2 = 7.5\] Then, add \(c\):\[7.5 + 17.5 = 25.0\]So, the output of statement (b) is `25.0`.

Evaluate Expression c

The expression is:\[a / \text{static_cast(b)} + 2 * c = 13 / 5.0 + 2 * 17.5\]First, divide \(a\) by \(b\):\[13 / 5.0 = 2.6\] Then, multiply 2 by \(c\):\[2 * 17.5 = 35.0\] Finally, add the two results:\[2.6 + 35.0 = 37.6\]So, the output of statement (c) is `37.6`.

Evaluate Expression d

The expression is:\[14 \, \% \, 3 + 6.3 + b / a = 14 \, \% \, 3 + 6.3 + 5 / 13\] First, find \(14 \% 3\):\[14 \, \% \, 3 = 2\] Then, perform \(b / a\): \[5 / 13 \approx 0.3846\]Finally, add the results:\[2 + 6.3 + 0.3846 \approx 8.6846\] So, the output of statement (d) is approximately `8.6846`.

Evaluate Expression e

The expression is:\[\text{static_cast(c)} \, \% \, 5 + a - b = 17 \, \% \, 5 + 13 - 5\] First, find \(\text{static_cast(c)} = 17\), then:\[17 \, \% \, 5 = 2\] Next, add \(a - b\):\[13 - 5 = 8\] Finally, add the results:\[2 + 8 = 10\] So, the output of statement (e) is `10`.

Evaluate Expression f

The expression is:\[13.5 / 2 + 4.0 * 3.5 + 18\]First, divide 13.5 by 2:\[13.5 / 2 = 6.75\]Multiply 4.0 and 3.5:\[4.0 * 3.5 = 14.0\]Add 18:\[6.75 + 14.0 + 18 = 38.75\]So, the output of statement (f) is `38.75`.

Key concepts

Output Evaluation

In C++ programming, one of the first challenges you may encounter is understanding how output evaluation works. Output evaluation is the process where an expression is computed and its result is displayed, typically using the `cout` statement. For instance, in the expression `a + b - c`, each variable will be accessed, any arithmetic operations will be performed, and the final result will be printed to the console.

Understanding how these operations are sequenced, especially in complex expressions, helps in debugging and predicting the behavior of your code. The key is to follow the operations step-by-step, evaluating each part of the expression before moving to the next. For example, in statement (a) above:

• Compute the sum of `a` and `b`.
• Subtract the result of the sum from `c`.
• Output the final result.

By methodically applying these steps, you can consistently anticipate the output for any given expression.

Data Types and Casting

Data types are a foundational aspect of C++ programming, dictating the kind of data a variable can hold. Common data types include `int` for integers and `double` for floating-point numbers. Proper handling of these data types ensures correct calculations and prevents errors.

Sometimes, you might need to convert or "cast" a variable from one data type to another. This process is known as type casting. In C++, you can perform an explicit type conversion using `static_cast`. For example, if you have an integer `b` that needs to be used in a floating-point calculation, like in expression (c) above, you type cast it:

• `a / static_cast(b)` changes `b` from an integer to a double for precise division.

Understanding how casting affects your variables is crucial in programming as it impacts the precision and accuracy of arithmetic operations.

Arithmetic Operators

Arithmetic operators are the backbone of performing calculations in C++. The basic ones include:

• Addition `+`
• Subtraction `-`
• Multiplication `*`
• Division `/`
• Modulo `%`, which gives the remainder of division.

Operators follow a precedence that dictates the order of operation unless parentheses are used to explicitly define it. For example, multiplication and division have a higher precedence than addition and subtraction. In expression (d), the modulo operation `14 % 3` is performed before the addition to `6.3` and the division of `b / a`.

Understanding these operators and the rules they follow will help you write clear and efficient C++ code. Be mindful of operator precedence to ensure that expressions are evaluated in the intended order.

Step-by-Step Problem Solving

Approaching C++ problems with a step-by-step methodology is immensely beneficial. It involves breaking down complex problems into manageable parts and solving each one before moving on to the next. This method often prevents errors and assists in debugging.

Consider expression evaluation: each part of the expression is separately calculated following the order of operations. When faced with a new problem, begin by listing the required operations and make note of any casts or conversions.

For instance, in expression (e) from the original exercise:

• First, compute the modulo operation.
• Next, perform addition or subtraction as defined.
• Finally, compile all results for the final output.

By approaching each step systematically, you build a clear pathway to the solution. This practice not only helps manage complex tasks but also enhances your understanding and capability in programming.