In C++ (const parameters and integer arithmetic), determine the output of the following code. Consider integer operator precedence and the final multiplication by 0.2.
#include
const double CuriousTabConstant(const int, const int = 0);
int main()
{
const int c = 2;
cout << CuriousTabConstant(c, 10) << " ";
cout << CuriousTabConstant(c, 20) << endl;
return 0;
}
const double CuriousTabConstant(const int x, const int y)
{
return ( (y + (y * x) * x % y) * 0.2 );
}
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AThe program will print the output 2 4.
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BThe program will print the output 20 40.
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CThe program will print the output 10 20.
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DThe program will print the output 20 4.50.
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EThe program will report compile time error.
Answer
Correct Answer: The program will print the output 2 4.
Explanation
Introduction / Context: The challenge is to simplify a mixed expression with integer multiplication, modulus, and then a scaling by a floating constant. Because of integer properties, one term collapses to zero, leaving a simple proportional result based solely on y.
Given Data / Assumptions:
x = 2; calls usey = 10andy = 20.- Expression:
y + (y * x) * x % yall in integer arithmetic, then multiplied by0.2.
Concept / Approach: For any integers k and nonzero y, (k * y) % y = 0. Here (y * x) * x is clearly a multiple of y, so the modulus term vanishes. The remaining value is simply y, and the final multiplication by 0.2 yields y * 0.2.
Step-by-Step Solution:
Simplify: (y * x) * x % y = 0 So return = (y + 0) * 0.2 = y * 0.2 For y=10 → 10 * 0.2 = 2 For y=20 → 20 * 0.2 = 4Verification / Alternative check: Replacing 0.2 with 1.0/5.0 shows the same result; double formatting by default often prints without fixed decimals (e.g., "2 4").
Why Other Options Are Wrong:
- 20 40 or 10 20: Ignore the final scale factor.
- 20 4.50: Arithmetic is not producing 4.5 for the second value.
- Compile-time error: Code is legal and compiles.
Common Pitfalls: Misapplying operator precedence or assuming modulus binds differently; here parentheses make the intended grouping explicit.
Final Answer: The program will print the output 2 4.