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[CSE10200] Programming Basis
(프로그래밍 기초)
Chapter 3
Seungkyu Lee
Assistant Professor, Dept. of Computer Engineering
Kyung Hee University
Expressions
• A sequence of operands and operators that reduces to a single value
• Example:
2 + 5
Operand
Operator
Expression
C++ Expression Format
Primary Expressions
• Three types of primary expressions
Binary Expressions
Binary Expression -- Multiplicative Expressions
10 * 12
20 / 4
5 % 2 ??? Modulus Operator (%) (나머지 연산)
5 % 2 1
5 % 3 2
6 % 3 0
Try!!!
Binary Expression -- Additive Expressions
• Additive expression – 3 + 5, 4 – 6
Assignment expressions • The assignment expression has a value and a result.
– Value: the value of the expression on the right of the assignment operator (=).
– Result: the result copies the expression value to the left of the assignment operator.
• The left operand in an assignment expression must be a single variable.
Simple Assignment
• Consists of simple algebraic expressions
• Examples
Try!!!
Compound Assignment
• Shorthand notation for a simple assignment
• Examples
Try!!!
Postfix Expressions
Remember!
(a++) is (a = a + 1)
(a– –) is (a = a – 1)
Try!!!
5) Unary expressions
Remember!
(++a) is (a = a + 1)
(– –a) is (a = a – 1)
Try!!!
Example code
#include <iostream> #include <iomanip> using namespace std; int main () { int a = 4; cout << "value of a : " << setw(2) << a << endl; cout << "value of ++a : " << setw(2) << ++a << endl; cout << "new value of a: " << setw(2) << a << endl; cout << "value of a++ : " << setw(2) << a++ << endl; cout << "new value of a: " << setw(2) << a << endl; return 0; }
Try!!!
Operator Precedence • Which operator will
be evaluated first?
• Each operator has one of 18 precedence levels
• Look at the cover page of the book
Operator Precedence Examples
• 2 + 3 * 4
( 2 + ( 3 * 4) )
• -b++
( -( b++ ) )
Operator Associativity • Determine the
evaluation order of the operators having the same precedence
• Left associativity vs. Right associativity
Operator Associativity Examples
• Left associativity
• Right associativity
Try!!!
Statements
• A block of instructions
• Types of statements
Expression Statements • Examples
a = 2;
a = b = 3;
a = 4 + 5;
a = b + (45 / c) + 22;
a++;
* An expression statement is terminated with a semicolon (;). The semicolon is a terminator, and it tells the compiler that the statement is finished.
Compound Statements
• A block of multiple statements
Sample Programs
Try!!!
Sample Programs
Try!!!
• Additional Practice!!!
Sample Programs
Try!!!
Sample Programs
Try!!!
Try!!!
Try!!!
Try!!!
Try!!!