+ 13

Clarification of challenge question from Hatsy Rei

What is the output of this code? char a = 'a'; static_cast <int>(a)+1 //what does this mean? cout <<a; Ans:a How did we get the output as 'a'?

14th Apr 2017, 4:15 AM
Pixie
Pixie - avatar
10 ответов
+ 18
*Star wars Dark Side music plays* *Space capsule opens, gas everywhere, Darth Rei steps out* Welcome to the Dark Side... !!!! --- --- char a = 'a'; static_cast <int>(a)+1; cout <<a; What static_cast does here, is to cast (a) to int ASCII value and return to where it is called. The catch here is that static_cast is not printed, and static_cast doesn't 'convert' what is stored in a variable - It simply casts them. So, in order to correctly cast character a to int and output it, the code should have been: char a = 'a'; cout << static_cast <int>(a); Adding 1 to the static_cast statement was just a trick. Some may think that char a would end up storing 'b', but no.
14th Apr 2017, 10:52 AM
Hatsy Rei
Hatsy Rei - avatar
+ 13
In case you wanted the output to be 'b'... There are a few ways to do it, but if you wanted to go for static_cast... char a = 'a'; cout << static_cast<char>(static_cast<int>(a) + 1);
14th Apr 2017, 11:12 AM
Hatsy Rei
Hatsy Rei - avatar
+ 11
It's a modification of typing, on a line, all by itself: a; If you want to compare, try exactly that (stating a value) in Python interactive mode vs. running a program: What should the 'program runner' (immediate mode interpreter vs. runtime/compiler) do with a statement with no left-hand side?
14th Apr 2017, 5:10 AM
Kirk Schafer
Kirk Schafer - avatar
+ 9
Thanks for the clarification, Hatsy Rei! 🍪
14th Apr 2017, 10:55 AM
AtK
+ 9
Tyvm ☺
14th Apr 2017, 11:13 AM
Pixie
Pixie - avatar
+ 8
Go through a very good article on data type conversion at http://www.cplusplus.com/doc/tutorial/typecasting/
14th Apr 2017, 5:12 AM
देवेंद्र महाजन (Devender)
देवेंद्र महाजन (Devender) - avatar
+ 8
Is it covered in the C++ tutorial here? Thanks for the answer, luka! 👍
14th Apr 2017, 10:07 AM
AtK
+ 8
@Hatsy Exactly where I went wrong haha. I typed in 'b' as the answer and was very confused when it was wrong. Thanks for clearing it up Edit: Can you give the syntax in case I wanted the output to be "b'
14th Apr 2017, 10:55 AM
Pixie
Pixie - avatar
+ 8
One thing I hoped someone would add here (maybe Ace, if he'd seen it): test.cpp:6:21: warning: expression result unused [-Wunused-value] static_cast <int>(a)+1; //what does this mean? ~~~~~~~~~~~~~~~~~~~~^~ 1 warning generated. SoloLearn and many online compilers have warnings OFF or...hidden/sometimes I see them (the -W shows which of mine fired). Some compilers, in certain modes, will even OMIT lines (if inlined), causing weird bugs (if you intend to call while discarding the result).
14th Apr 2017, 4:01 PM
Kirk Schafer
Kirk Schafer - avatar
+ 7
looks like typical c++ sorcery to me
14th Apr 2017, 4:51 AM
Edward