+1

What is it? Parsing code from a quiz.

#include <iostream> using namespace std; int main() { int i = 0; cout << (i = 0 ? 1 : 2 ? 3 : 4); return 0; }

3/31/2020 6:19:07 PM

Vasiliy

32 Answers

New Answer

+3

if ( i = 0 ) // assignment not comparison returns 0 cout << 1; else if (2) cout << 3; else cout << 4; [I was wrong read other comments 4more info] Answer 3 https://www.sololearn.com/Discuss/42804/?ref=app

+3

if(0){ //0 is false i = 1; }else if(2){ // 2 is true i = 3; }else{ i = 4; } cout << i;

+2

Why not? Maybe the author wanted to say i==0 instead of i = 0. But apart from that I thing everything is fine. Did you get the code from a quiz?

+2

The code prints 3.

+2

It printed 1 for me , but for urself i u wanna try both ternaries u can go like this . cout<<(i==0?1:2); cout<<(i==0?3:4); //output : 13

+2

Finally, I realized this code corresponds to this: if ((i=0) == true){ i = 1; }else if ((i=2) != true){ i = 3; }else{ i = 4; } cout << i; P. S: "the last "else" statement is ": 4", it is only necessary for the compiler to accept the abbreviated syntax for writing "if ... else if ... else ..." "

+2

Vasiliy you are right! Assignment operator has lower precedence I missed that. But i = 2 is true. david chongo ? : Ternary operator takes an expression and returns something based of the boolean value of that expression: (exp)?(returnIfTrue):(returnIfFalse) Read above code like this: cout<< (i= (0 ? 1 : ( 2 ? 3 : 4 ) ) Both operators are taking 3 operands but the first operator's third operand is just another expression containing a ternary operator. Abhay S G shankur 0 is false so ans can't be 1

+2

Александр J, я не ставил цель выяснить какой будет вывод, я ставил цель выяснить как этот код работает и насколько он написан корректно, так что это как раз и принципиально в данном случае. P. S: "ошибка не в выражении, даже если вы измените на присвоение, всё равно ваш код ничего не выведет".

+1

I tried with "==", all the same, only the first part of the code works correctly. Under no circumstances can you print 4.

+1

+1

Kevin Star, 👏bravo, finally you and I have reached the truth.

+1

Kevin Star, that's just the "else" here is completely useless, enough like this: if(0){ i = 1; }else if(2){ i = 3; } cout << i; But with the help of a tennis operator you can’t write it like this: cout << (i = 0 ? 1 : 2 ? 3); - will give an error.

+1

Дальше, хуже. Только, предположения :( JavaScript для меня, пока, только, язык учебных моделей, а не реальных проектов, поэтому, из дискуссии самовыпиливаюсь до достижения приемлемого багажа знаний. Впрочем, используя, ваши высказывания, в качестве паттерна, - свою логику, я - тоже, объяснял этажом выше :) Пусть, она, и, строилась на неверных исходных предпосылках.

0

Kevin Star, I assumed something similar, but then I don’t understand how it works...

0

Kevin Star, after a long analysis of this code, I still came to the conclusion that it was not written correctly and did not work as it should.

0

Although with the standard: "if ... else if ... else... " everything works flawlessly.

0

From the quiz the answer should be 2 I think

0

david chongo, do not rush to the conclusion.

0

Vasiliy, I understand. I should have added to say perhaps there is something missing. In my view, since the conditional operator takes 3. If then we don't have those 3 inputs, I am not sure if we can proceed any further. Here now I would want to agree somehow with suggestion by Farnaz.A above

0

The ternary or conditional statement checks a condition and then assigns true or false result. In this question there is use of one '=' which is the assignment operator and not a conditional operator like '=='. So it appears really that what was needed was the conditional operator to test the value of the variable as being equivalents to the declared value of i=0. And depending on the result we can then attribute a true or false to the variable.