58

x=57
y=59

57
59

57
94

55 

59

57 94

57 94


{x=y++ + x++;}
equal to
{
x=y+x;//35+20
x++; //56
y++; //36
}


y=++y + ++x;
equal to
{
++y;//37
++x;//57
y=y+x;//37+57
}

So x=57
y=94

while calculating the x value,x & y values are post 
incremented.So the values of x & y are added and then 
incremented i.e. x=56,y=36
while calculating the y value,x & y values are 
preincremtned,so x & y values are incremented and then 
added i.e. x=57,y=37.
so x=57
y=57+37=94.

x=57
y=94

55 59

correct answer  is 57 94

55  93

Here this should make it easier for you...
                  
Problem_________|___Solution__|

int x=20, y=35;    (here the values of x,y are apparent.)

x = y++ + x++;     (x=y+x+1) or(x = 35 + 20 + 1)x  = 56
                   But; you incremented y, its now = 36

y = ++y + ++x;     (y =(y+1)+(x+1)) or(y=1+36+1+56)y = 94
                   This is the second time you incremented
                   x so it is now = 57. 


The reason that you are getting different increases
for x and y is that when you use statement(x=x++) you are 
first stating that x is = to x, and then 'increment x.
when you use statemnt(x=++x) you are first 
stating 'increment x, then that x is = to x.

look at the code and description in the chart below.

table:
code    =  meaning;
int x=2
int y=2
-------------------|
(x=x++) =  "x = x, x + 1" (increment happens after)
(x=++x) =  "x = (x+1)"    (increment happens before)
(x=y++) =  "x = y, y + 1" (increment happens after)
(x=++y) =  "x = (y+1)"    (increment happens before)

if you want to add y to x and then increment y use this 
statement:

x+=y++

if you want to increment y and then add it to x use this 
statement:

x+=++y

Answer is 57 and 94
bcoz precedence of the ++ operator is more than + operator
so y++ and x++ will be evaluated first before addition so
y++ will be 36 and x++ will be 21 after that 36 + 21 = 57
similar reasoning for y = ++y + ++x

The program results in an undefined behaviour. You're wrong
if you have a certain answer. Learn more on the wikipedia
http://en.wikipedia.org/wiki/Sequence_point