Introduction to Programming 5 Operators2 Dr Khizar Hayat

Introduction to Programming – 5 Operators-2 Dr. Khizar Hayat Associate Prof. of Computer Science

Operators • Arithmetic operators • Assignment operator, i. e. = – Compound assignment or arithmetic assignment operators • Increment and Decrement operators – Pre-increment – Post-increment • Relational operators • Logical Operators • Bit-wise logical operators

Relational Operators • The relational operators evaluate to either true (1) or false (0) • In C++ the relational operators are: 1. 2. 3. 4. 5. 6. == Equal to != Not equal to > Greater than < less than >= Greater than or equal to <= less than or equal to • Never confuse == (equal to) with = (assignment or gets)

Examples • What would the following expression evaluate to? • (7==5) //false 0 • (5>4) //true 1 • (3!=2) //true 1 • (6>=6) //true 1

Examples • What would the following expression evaluate to? Let int a=2, b=3, c=6; • (a==5) • (a*b>=c) //false //true • (b+4>a*c) //false • ((b=2)==a) //true

Logical Operators • The logical operators also evaluate to either: true (1) or false (0) • In C++ the Logical operators are: 1. 2. 3. ! NOT && AND || OR Unary Binary draw truth table • Bitwise logical operators are: 1. 2. 3. 4. 5. & bitwise AND | bitwise OR ^ bitwise XOR << left shift >> right shift

The ternary operator (? : ) if-then-else • Also called the conditional operator • Use: condition ? result 1 : result 1 (if true) (if false) • Examples: – 7==5? 4: 3; //return 3 – 7==5+2? 4: 3; //return 4 – a>b? a: b; /*return whichever greater, a or b */

Example ternary operator #include<iostream> using namespace std; int main() { int a, b, c; a=2; b=7; c= (a>b)? a: b; cout<<“c = "<<c<<endl; return(0); }

Explicit Typecasting • For converting identifier/variable of one data type to other. • Use parenthesis () • Two ways: – The C- way: enclose the new data type in parentheses, e. g. int i; float f=3. 14; i=(int)f; // i would contain 3 – The function way: write the new data type enclose the old variable in parenthesis, e. g. int i; float f=3. 14; i=int(f); // i would contain 3

sizeof() • Accepts one parameter, either the data type or variable name, and • returns the size in bytes of that type or type of variable. • The return data type is int. • For example, the lines: int a; short b; a= sizeof(char); cout<<a; // would print 1 a= sizeof(b); cout<<a; // would print 2

Operator Precedence High Low Operator Name Primary scope resolution Associativity Operators left to right : : Primary left to right () [ ] Unary Multiplicative Additive Bitwise Shift Relational Equality Bitwise AND Bitwise XOR Bitwise OR Logical AND Logical OR Conditional /Ternary Assignment Comma right to left to right left to right left to right to left right to left to right ++ -- + - ! * / % + << >> < > <= >= == != & ^ | && || ? : = += -= *= /= <<= >>= %= &= ^= |= , Associativity refers to the order when operators of same precedence are there in the same expression

Examples • x=2*5*5+3*5+7; //72 - from notes • z=7*10 -5%3*4+9; //71 • z=7*(10 -5)%3*4+9; //17 • y=5*(4+(10 -6)/2*3)+5; //55