- Title Page
- Copyright Page
- Dedication Page
- Contents
- New Features in C++11
- Preface
- Chapter 1. Getting Started
- Part I. The Basics
- Contents
- Chapter 2. Variables and Basic Types
- Chapter 3. Strings, Vectors, and Arrays
- Chapter 4. Expressions
- Contents
- 4.1. Fundamentals
- 4.2. Arithmetic Operators
- 4.3. Logical and Relational Operators
- 4.4. Assignment Operators
- 4.5. Increment and Decrement Operators
- 4.6. The Member Access Operators
- 4.7. The Conditional Operator
- 4.8. The Bitwise Operators
- 4.9. The sizeof Operator
- 4.10. Comma Operator
- 4.11. Type Conversions
- 4.12. Operator Precedence Table
- Chapter Summary
- Defined Terms
- Chapter 5. Statements
- Chapter 6. Functions
- Chapter 7. Classes
- Part II. The C++ Library
- Contents
- Chapter 8. The IO Library
- Chapter 9. Sequential Containers
- Chapter 10. Generic Algorithms
- Chapter 11. Associative Containers
- Chapter 12. Dynamic Memory
- Part III. Tools for Class Authors
- Contents
- Chapter 13. Copy Control
- Chapter 14. Overloaded Operations and Conversions
- Contents
- 14.1. Basic Concepts
- 14.2. Input and Output Operators
- 14.3. Arithmetic and Relational Operators
- 14.4. Assignment Operators
- 14.5. Subscript Operator
- 14.6. Increment and Decrement Operators
- 14.7. Member Access Operators
- 14.8. Function-Call Operator
- 14.9. Overloading, Conversions, and Operators
- Chapter Summary
- Defined Terms
- Chapter 15. Object-Oriented Programming
- Contents
- 15.1. OOP: An Overview
- 15.2. Defining Base and Derived Classes
- 15.3. Virtual Functions
- 15.4. Abstract Base Classes
- 15.5. Access Control and Inheritance
- 15.6. Class Scope under Inheritance
- 15.7. Constructors and Copy Control
- 15.8. Containers and Inheritance
- 15.9. Text Queries Revisited
- Chapter Summary
- Defined Terms
- Chapter 16. Templates and Generic Programming
- Part IV. Advanced Topics
- Contents
- Chapter 17. Specialized Library Facilities
- Chapter 18. Tools for Large Programs
- Chapter 19. Specialized Tools and Techniques
- Appendix A. The Library
- Contents
- A.1. Library Names and Headers
- A.2. A Brief Tour of the Algorithms
- A.2.1. Algorithms to Find an Object
- A.2.2. Other Read-Only Algorithms
- A.2.3. Binary Search Algorithms
- A.2.4. Algorithms That Write Container Elements
- A.2.5. Partitioning and Sorting Algorithms
- A.2.6. General Reordering Operations
- A.2.7. Permutation Algorithms
- A.2.8. Set Algorithms for Sorted Sequences
- A.2.9. Minimum and Maximum Values
- A.2.10. Numeric Algorithms
- A.3. Random Numbers
- Index
- Add Pages
4.10. Comma Operator
The comma operator takes two operands, which it evaluates from left to right. Like the logical AND and logical OR and the conditional operator, the comma operator guarantees the order in which its operands are evaluated.
Exercises Section 4.9
Exercise 4.28: Write a program to print the size of each of the built-in types.
Exercise 4.29: Predict the output of the following code and explain your reasoning. Now run the program. Is the output what you expected? If not, figure out why.
int x[10]; int *p = x;
cout << sizeof(x)/sizeof(*x) << endl;
cout << sizeof(p)/sizeof(*p) << endl;
Exercise 4.30: Using Table 4.12 (p. 166), parenthesize the following expressions to match the default evaluation:
(a) sizeof x + y
(b) sizeof p->mem[i]
(c) sizeof a < b
(d) sizeof f()
The left-hand expression is evaluated and its result is discarded. The result of a comma expression is the value of its right-hand expression. The result is an lvalue if the right-hand operand is an lvalue.
One common use for the comma operator is in a for loop:
vector<int>::size_type cnt = ivec.size();
// assign values from size... 1 to the elements in ivec
for(vector<int>::size_type ix = 0;
ix != ivec.size(); ++ix, --cnt)
ivec[ix] = cnt;
This loop increments ix and decrements cnt in the expression in the for header. Both ix and cnt are changed on each trip through the loop. As long as the test of ix succeeds, we reset the current element to the current value of cnt.
Exercises Section 4.10
Exercise 4.31: The program in this section used the prefix increment and decrement operators. Explain why we used prefix and not postfix. What changes would have to be made to use the postfix versions? Rewrite the program using postfix operators.
Exercise 4.32: Explain the following loop.
constexpr int size = 5;
int ia[size] = {1,2,3,4,5};
for (int *ptr = ia, ix = 0;
ix != size && ptr != ia+size;
++ix, ++ptr) { /* ... */ }
Exercise 4.33: Using Table 4.12 (p. 166) explain what the following expression does:
someValue ? ++x, ++y : --x, --y
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