C programming

Question

Consider 2 cases:

1. Call by value result

2. Call by reference

int x = 10 ;
main ( )
{
P(x); printf (x);
}
P ( int a)
{
If ( a ≤ 40 )
{
a = a +10;
P(a);
x=a+10;
}
}
Please explain this in the above referenceIn case of call by reference the value of the actual parameter is simultaneously updated whereas, in case of call by value result, the final value of a formal parameter is passed to actual.
Any example in which these 2 will differ in output(especially in case of function calls)?

Comments

a=1, b=2;
P(a,b);
P(x,y)
{
    x=x+2;
    a=x*y;
    x=x+1;
}

While trying to print value of 'a' which was one of the parameters passed the two passing mechanisms will give different results.

For call by ref: a=7

For call by value result: a=4

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Got this same example in a vedio.
View this:

int x = 10 ;
main ( )
{
P(x); printf (x);
}
P ( int a)
{
If ( a ≤ 40 )
{
a = a +10;
P(a);
x=a+10;
}
}
Please explain this in the above reference

---

Do you know the answers? I am getting x=90 for call by ref and x=50[EDITED] for call by value result.

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Ok..I have done something wrong in call by ref..have to check it..

manisha11 I checked it..

I tried running the prog by call by ref..it is giving 90 only :/

#include<stdio.h>

int x = 10;
void P(int *a)
{
if (*a <=40 )
{
*a = *a +10;
P(a);
x=*a+10;
}
}

main ( )
{
P(&x); 
printf("%d",x);
}

 

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@MiniPanda

what u get in call by value result?

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I got 50

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Hi @miniPanda
Your answer is right.(apology for the hassle:P)
If you can please explain the process?

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call by value: 50  ( call by value changes only in copy data but not original )

call by refernce: 90

plz check??

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30 cal by value

50 cal by value result

90 cal by ref

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@MiniPanda

how 50 in call by value result?

I am getting more :(

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I tried my best explaining it through a diagram. It became very unclean though. But it is really difficult for me to show how actually it works with a diagram :P

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ok after after 50 in every call 50 stored as result just like call by reference?

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Yes srestha ..happy that it is understandable from this diagram :P

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@MiNiPanda thanks a lot!