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Operator precedence

Can some one explain the following code ? #include<iostream> using namespace std; int main(){ int a = 5; cout<<a&&0; return 0; } #include<iostream> using namespace std; int main(){ int a = 5; char b = ‘A’; cout<<a|b; return 0; } #include<iostream> using namespace std; int main(){ int a = 3; cout<<(a>>1)%3; return 0; }

15th Jan 2022, 9:07 PM
Super
4 Answers
+ 2
Super I made the following program for you. And I hope that all your questions have an answer in there. If you declare a new variable that have the AND or OR operation, the resulted is the expected one: int a = 5; int b = a && 0; If you use AND or OR in a cout, the result is not always the expected one: cout << a && 0 gives 5 instead of 0, the correct one. Or cout << (a && 0) give 0 which is correct. While cout << "(5&&0)" is a simple string (5&&0) will be as output. https://code.sololearn.com/cQK6XGZu8H4F/?ref=app
16th Jan 2022, 12:19 AM
Romeo Cojocaru
Romeo Cojocaru - avatar
+ 2
(continue to the previous message) if you do OR operation on those 2 binary values: 0000 0101 OR 0100 0001 -‐--------------- 0100 0101 So, if my calculations are right it should print 'A'. Finally, in the 3rd program you have (a>>1)%3. The >> operator is also from bitwise operator category, specifically the bitwise right shift operator. It can be translated as dividing by 2 as many times specified, in your case one time devided by 2. So, 3 / 2 is 1 (as a integer). Then 1 % 3 is the Modulus operator or the Remainder or Perfect Divisibility operator. 1%3 has the reminder 1. So, 1 will be printed. Bonus: cout <<, where << is not a bitwise operator. It is called the insert operator. In case of cin >>, >> is called the extracting operator. In conclusion, I recommend you to take the C course first and the C++ after.
15th Jan 2022, 9:36 PM
Romeo Cojocaru
Romeo Cojocaru - avatar
+ 1
You have not one code, but 3 programs in C++. Each programs starts with the pre-processor directive #include. The pre-processor directive #include is used in the first stage of program executing, when the pre-processor adds to your program all the source code present in the iostream.hpp (which is a library). Next, std is a namespace that contain all the C++ functionality under a single scope. main() is the entry point of every C++ program. It has no input parameters and returns an integer. a is an integer variable initialized with 5. cout is the printing function or displaying on std. a&&0 is a Logical operation, where && is logical AND, it means 5 AND 0 or can be translated to TRUE AND FALSE. It will print 0. In the 2nd program you have a|b or 5 OR 'A', where | is a bitwise operator, bitwise OR. I'm not sure what will print, and I don't want to test your program. You can do it yourself. I guess it will print a number in binary form (5 is 0000 0101 and 'A' in ASCII is 65 which is in binary 0100 0001
15th Jan 2022, 9:26 PM
Romeo Cojocaru
Romeo Cojocaru - avatar
0
Thanks for the reply Romeo Cojocaru I have a follow up question , if you dont mind What causes different result when you are using a “(5&&0)” and cout <<5&&0 The first one hase a vlaue of 0 , but the second one has a value of 5 Can you explain the difference
15th Jan 2022, 9:54 PM
Super