Prefix Postfix
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The document discusses increment and decrement operators in C++. It provides examples of using these operators in both prefix and postfix form and evaluates expressions involving these operators. Several examples are given that demonstrate evaluating expressions with increment and decrement operators. Questions involving the output of code snippets using these operators are also provided.
![Priority of Operators and Associativity Left Comma , 11 Right Assignment = += -= *= /= %= 10 Right Conditional ?: 9 Left Logical Op. && || 8 Left Relational Op. == != 7 Left Relational Op. < <= >= > 6 Left Arithmetic Op. + - 5 Left Arithmetic Op. * / % 4 Right ++ -- ! & * (type) + - 3 Left ()[]->sizeof 2 Left Scope :: 1 associativity Description Operator Priority](https://image.slidesharecdn.com/prefix-postfix-1220980481065867-9/85/Prefix-Postfix-6-320.jpg)
Prefix Postfix
- 1. Increment & Decrement operators (Postfix and Prefix) Ms.Nita Arora KHMS
- 2. Increment operator (++) Increases the value stored in a variable by 1 a++ a+=1 a=a+1 are all equivalent in functionality.
- 3. Increment operator (++) can be used in PREFIX and POSTFIX form. int B=3; int A=++B; //output B=4 // A=4 int B=3; int A=B++; //output B=4 // A=3
- 4. Decrement operator (--) Decreases the value stored in a variable by 1 a-- a - =1 a=a-1 are all equivalent in functionality.
- 5. Decrement operator (--) can be used in PREFIX and POSTFIX form. int B=3; int A=--B; //output B=2 // A=2 int B=3; int A=B- -; //output B=2 // A=3
- 6. Priority of Operators and Associativity Left Comma , 11 Right Assignment = += -= *= /= %= 10 Right Conditional ?: 9 Left Logical Op. && || 8 Left Relational Op. == != 7 Left Relational Op. < <= >= > 6 Left Arithmetic Op. + - 5 Left Arithmetic Op. * / % 4 Right ++ -- ! & * (type) + - 3 Left ()[]->sizeof 2 Left Scope :: 1 associativity Description Operator Priority
- 7. Associativity In case there are several operators of same priority, which one must be evaluated before- Leftmost Rightmost
- 8. Evaluation of expressions involving ++ and -- operators in postfix and prefix form PROBLEM AREA
- 9. Examples
- 10. #include <iostream.h> #include <conio.h> void main() { clrscr(); cout <<"\n************* EVALUATION OF EXPRESSIONS *************** \n\n"; int a=10,b=20,c=30; cout<<"a="<<a<<" b="<<b<<" c="<<c; int z=(a++)*c/a+b; cout <<"\nz=(a++ )*c/a+b = "; getch(); cout<<z; } Example 1
- 11. Example 2 #include <iostream.h> #include <conio.h> void main() {clrscr(); cout <<"\n** EVALUATION OF EXPRESSIONS ***\n\n"; int a=10,b=20,c=30; cout<<"a="<<a<<" b="<<b<<" c="<<c; z=++a*c/a+b; cout <<"\nz=++a*c/a+b = "<<; getch(); cout<<z; }
- 12. #include <iostream.h> #include <conio.h> void main() {clrscr(); cout <<"\n************* EVALUATION OF EXPRESSIONS ****************\n\n"; int a=1,b=2,c=3; cout<<"a="<<a<<" b="<<b<<" c="<<c; z= b+ c^a * ++b ; cout <<"\nz=b+c^a * ++b; = "; cout <<"\nAnswer is :(3+3)^(1*3) \n"; cout <<"\n :(6)^(3) \n"; cout <<"\nIn Binary :(110) XOR (011) \n"; cout <<"\n :(101) \n"; cout <<"\nIn Decimal Answer is : \n"; getch(); cout<<z; } Example 3
- 13. #include <iostream.h> #include <conio.h> void main() {clrscr(); cout <<"\n* EVALUATION OF EXPRESSIONS *\n\n"; z=45; int q=45; cout<<"\nq="<<q; cout<<"\n-q--="<<-q--; cout<<"q= " <<q; getch(); } Example 4
- 14. 6. What is the screen output? int a=20; a += a++ + ++a ; cout << a; 5. What is the screen output?    int i, j, k, m, ans;     i = 0;     j = -1;     k = 0;     m = 1;;     ans = i++ && ++j  || k || m++;     cout<<ans; 4. What is the screen output?     int i, j, k, ans;     i = 1;     j = 2;     k = 3;     ans = ++i *  j -  k--;     cout<<ans; 3. What is the screen output?     int i, j, k, ans;     i = 1;     j = 2;     k = 3;     ans = i++ *  j -  --k;     cout<<ans; 2. What is the screen output?     int a, b;     a = 6;     b = ++a -1;     cout<<"a = " << a << endl;     cout<<"b = " << b << endl; 1. What is the screen output?     int a, b;     a = 6;     b = a++ -1;     cout<<"a = " << a <<endl;     cout<<"b = " << b <<endl; Â
- 15. Evaluate the following c++ expressions where a, b, c are integers and d and f are floating point numbers. The values are a = 5, b=3 and d=1.5 f=a+b/a; c=d*a+b; c=a++ * d +a; f=++b * b – a; c=a-(b++) * (--d);
- 16. Do you have any QUESTIONS ?
Editor's Notes
- #2: 1 1 The “operator” keyword Overloading Unary operators Overloading Binary operators Constructors as conversion routines Converting between basic and user-defined types LEAD IN: Overloaded Unary Operators