Answered: Using the following description, please…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Question

Using the following description, please replace the return line in C code;

* conditional: same as x ? y : z

* Examples:

* conditional(0,3,4) = 4

* conditional(1,3,4) = 3

* conditional(4,5,6) = 5

* conditional(-1,7,8) = 7

* Legal ops: ! ~ & ^ | + << >>

* Max ops: 16

int conditional(int x, int y, int z) {

return 2

}

You cannot:

1. Use any control constructs such as if, do, while, for, switch, etc.

2. Define or use any macros.

3. Define any additional functions in this file.

4. Call any functions.

5. Use any other operations, such as &&, ||, -, or ?:, not listed in the

the "Legal ops" list for the function.

6. Use any form of casting.

7. Use any data type other than int.

Expert Solution

Step 1: Replacing Conditional Operator with Bitwise Operations:

You can achieve the desired behavior using bitwise operations and arithmetic without using any control constructs or macros.

This replaces the return line while adhering to the given constraints:

1int conditional(int x, int y, int z) {
2  int mask = (!!x) + ~0; // 0xFFFFFFFF if x is non-zero, 0x00000000 if x is zero
3  return (mask & y) | (~mask & z);
4}
5

This code calculates a mask that is 0xFFFFFFFF if x is non-zero and 0x00000000 if x is zero. Then, it uses bitwise AND and OR operations to select either y or z based on the value of the mask, effectively achieving the same behavior as the conditional operator (? :).

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