GATE CSE 2012 | Question: 3

Question

What will be the output of the following C program segment?

 char inChar = 'A';
    switch ( inChar ) {
       case 'A' : printf ("Choice A \ n");
       case 'B' :
       case 'C' : printf ("Choice B");
       case 'D' :
       case 'E' :
       default : printf ("No Choice"); 
    }

• A. No Choice
• B. Choice A
• C. Choice A
  Choice B No Choice
• D. Program gives no output as it is erroneous

Comments

you have read right . It is correct

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@Rajat Agrawal007 To be more precise it should yield an integer value, like if its switch (7.0) then also compiler will throw error. So the concept is it must be an integer.

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Correct question would be

char inChar = 'A';
    switch ( inChar ) {
       case 'A' : printf ("Choice A \n");
       case 'B' :
       case 'C' : printf ("Choice B ");
       case 'D' :
       case 'E' :
       default : printf ("No Choice");
    }

Answer 1

There is a `space` in between the `\` and `n` in the printf of case ‘A’ and also no space after the printf for case ‘C’ in the original question (see-Q-no.-3). Due to this “Marks to All” was done.

Lets assume no space for “\n” in the printf for case ‘A’ and there is a space at the end of printf of case ‘C’.

When a case of a switch is matched, execution continues from the matched case until a “break” is encountered (any intermediate case labels simply gets ignored).

So, output of the given program is:

Choice A
Choice B No Choice 

Option C.

Comments

But in GATE mark was given for all.

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@Mithilesh Good eye :) (y)

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I believe output should be
Choice A

NO Choice

since inChar, 'A' is not equal to case constant, 'C' present in switch expression , "Choice B" wouldn't get printed

 

Pls clarify

Note : Marks were given for all in answer key of Gate exam

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 Arjun sir link not working 

http://stackoverflow.com/questions/33694700/im-missing-something 

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@ Arjun sir WHAT WE DO IN GATE EXAM IF THERE IS NO OPTION MATCHED.....????? 

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@Arjun Suresh Sir, If there were no space between / and n, then will option C be correct answer?

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yes.

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@srestha..... no,even if If there were no space between / and n, then also option c would not be correct answer.

@Arjun sir.. pls.verify this

correct ans would have been

Choice A

Choice B

i have taken this pic from dennis ritchie

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That statement is correct -- default will execute if no other case matches. But it does not say that default won't be executed if some other case matches.

Actually when some case matches all statements which follows are executed ignoring any labels. We have to explicitly use "break" to avoid this.

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ok sir....now i got it...default case is for the situation when case does not matches...but it can be executed even if any case matches.

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Why '\' after A is not in the output in case of correct output ?

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http://www.geeksforgeeks.org/gate-gate-cs-2012-question-9/ 

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@Arjun sir pls correct question ,there is no space between this progam

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Why '\' after A is not in the output in case of correct output ?

??

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@jatin khachane 1 "\" followed by something are predefined.

\ is a non printable character. If you want to print it, you have to do "\\".

Here "\ " has no meaning.

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Yes this condition is known as fall through

@ArjunSir

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‘\’ is used for line continuation or line extension.

Look below two programs. First gives error while second wouldn’t.

Program -1 :

 

Program -2 :

Notice one thing, we broke “Hello world” token in two lines. :)

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If the q had 

  case 'A' : printf ("Choice A \n");

Then the Output would be :-

Choice A 
Choice BNo Choice

Even this is not present in Option C.

Edit: Ok, there is a space after Choice B. So in new question, ans is Option C.

Thanks @Pranavpurkar for pointing it out. 

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@Abhrajyoti00

are you considering the space between (as it  is not the same in options)

1. Choice BNo Choice

B and N?

 

Answer 2

There is no break statement in  any case . If a case doesn’t contain break, then all the subsequent cases are executed until a break statement is found. That is why everything inside the switch is printed.

so ans is C

Answer 3

Syntax:

1. switch(expression)
2. {
3. case constant-exp1 : statements; break;
4. case constant-exp2: statements; break;
5. default: statements;
6. }

In switch case, the break statement is used to terminate the switch case. Basically it is used to execute the statements of a single case statement. If no break appears, the flow of control will fall through all the subsequent cases until a break is reached or the closing curly brace ‘}’ is reached.

In above , switch case don't have break statement , 

1. If inChar='A'  , flow control will execute all statements after Case A: till switch case end (in case any break states occurs between statement , it will terminated at the point but in above example we don't have any break statement, so whole switch block will execute).

Output : Choice A
               Choice B No Choice

In case if inChar='C' then output will be  Choice B No Choice.

it's not necessary that we should always add break statement for each cases in switch, including break statement in switch case is based on our requirement.

Answer is C

Answer 4

Answer: Option C

There is no break statement after case A, if there is no break statement then it will execute all the subsequent cases. So it will execute all those print statements. Hence option C. 

To know more about Switch statement refer this: https://www.geeksforgeeks.org/interesting-facts-about-switch-statement-in-c/ it will clear all the doubts.