c programming

Question

What will be the output of the program If characters 'a', 'b' and 'c' enter are supplied as input? #include<stdio.h> int main() { void fun(); fun(); printf("\n"); return 0; } void fun() { char c; if((c = getchar())!= '\n') fun(); printf("%c", c); }

[A]. abc abc [B]. bca [C]. Infinite loop [D]. c,b,a

Comments

I don't think any option rightly describes the situation.

After a, b and c are processed as input, the getchar() will be waiting for another input and will continue to wait.

Not exactly an Infinite Loop. But if I have to choose I'll go with Infinite loop.

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@ Warlock lord    i also selected that.But the answer is given d!

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Stack overflow should have been in option as there is a scenario of infinite recursion..

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@habib  waht do u think about D ?

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I guess it is a typing mistake by them. The condition should have been: 

if((c = getchar())!= 'c') 

Then it could have been D as the answer

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Ya in that case 'D' should have been the correct answer..

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D should be the correct answer. When it says that a, b, c are supplied as input, then it is implied that after typing abc it will terminate with a newline.

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Okay. So we know that for getchar() to accept a character we need to append any character whith a newline.

In this case if we wish to put a,b,c as our input the input array internally will have ['a','\n','b','\n','c','\n']

So by that logic the program above should only print 'a' along with a space preceding it.

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'\n' will be added only after the complete input has given, i.e abc. Consider the case when the input is given through a file.

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If the input abc are given separately as 'a','b' and 'c' (and not as 'abc' or 'a b c'), then there will be '\n' after every character only then getchar() will accept a,b and c separately . I even typed down a program and printed the output and turns out space does get appended after every character.

And this applies even if the input is given from a file.

Answer 1

Suppose input is given from the keyboard: When you give 'a' as input and press enter,

getchar() returns the first character in the input buffer (i.e. c = 'a'), and removes it from the input buffer. But other character (i.e. '\n') is still in the input buffer. c is checked with '\n' 'a' != '\n' and fun() is called again but now '\n' was already present in the input buffer so c = '\n'. The condition is checked again to be false. Thus '\n' is printed followed by 'a' from first call to fun(), followed by '\n' from main().Output: 2 lines first blank second has character a

'\n'--> blank line

a

If input is given as abc then '\n' Output: 2 lines first blank second has characters cba

'\n' --> blank line

cba