Difference between pre-increment and post-increment

[Kasya]

Difference between x++ and ++x;
Difference between x-- and --x;

[Banfa]

++x is pre-increment and x++ is post-increment that is in the first x is incremented before being used and in the second x is incremented after being used.

This is most easily demonstrated with a small program

#include <stdlib.h>
#include <stdio.h>
 
int main(int argc, char **argp)
{
    int x = 5;
 
    printf("x=%d\n", ++x);
    printf("x=%d\n", x++);
    printf("x=%d\n", x);
 
    return EXIT_SUCCESS;
}

The output of this program is

x=6
x=6
x=7

In the first printf statement x is incremented before being passed to printf so the value 6 is output, in the second x is passed to printf (so 6 is output) and then incremented and the 3rd printf statement just shows that post increment following the previous statement by outputting x again which now has the value 7.

[Kasya]

Difference between x-- and --x;

[Banfa]

I would have thought you could have modified the program I posted to find out, where ++ is increment -- is decrement, apart from that that act in a similar manor.

[Kasya]

Thanks!!!!!

[maan]

Thanks!!!!!

an other method
m+=1; is post increment
or m-=1 is post decrement

[JosAH]

an other method
m+=1; is post increment
or m-=1 is post decrement

Have you tried it? The value of the expression "m+=1" equals "m+1" so it is
more like a pre increment.

kind regards,

Jos

[maan]

yes i tried practicaly " m+1" is eqal to "m+=1"

"++m" is pre increment

if you have any other idea please reply

i'll wait 4 ur +ive response

Regardz Maan....

[JosAH]

yes i tried practicaly " m+1" is eqal to "m+=1"

"++m" is pre increment

Erm, yes that's what I wrote; you wrote that m+= 1 had the same value as
the *post* increment expression (see above).

kind regards,

Jos

[mistiq]

thank u buddy...i had the same question and ur answer really worked out:)

[chandu google]

i++ the post increment means after the after executing the value is increased. ++i is the preincrement it is before the executing the value is increased.

[cybosofttech]

++ operator is called increment operator . ++[variable] is called preincrement operator and [variable]++ is called post increment operator.

The preincrement operator first increment operator will increment the value stored in variable and then returns the stored value.

[Regila Mary]

what is the output of the following programs....

main()
{
  int c,i=5;
  if(i<10)
  {
     i++;
     c=i;
     cout<<c;
   }
}

what is the output????
Than,,,

main()
{
  int c,i=5;
  if(i<10)
  {
     ++i;
     c=i;
     cout<<c;
   }
}

what is the output????
I think the above 2 program got the same output. them y u use a pre and post incerment opretor?????

[donbock]

The difference between pre-increment and post-increment is whether the increment takes place before or after the value is used. Line 6 (in both snippets) does not use the value, so there is no discernible difference between the two kinds of increment.

To see a difference, combine lines 6 and 7 into a single line; for example:

c = i++;

or

c = ++i;

[AceInfinity]

@maan - No, you're wrong... m+1 is not the same as m+=1. m+1 holds the value of m after m+=1, but for m+1, the value of m will still be (m+1)-1, because that added 1 is not stored in the variable m.

edit: m=m+1 is the same as m+=1.

[vinoth102]

x=5, y=5
x=y++ //Ans: x=5, y=6


x=5, y=6
x=++y; //Ans: x=6, y=6

[donbock]

@vinoth102 The initial condition for your second example should be y=5.

[Sherin]

Pre-increment

Pre increment operator is used to increment variable value by 1 before assigning the value to the variable.


Syntax:

a = ++x;


Post-increment

Post increment operator is used to increment variable value by 1 after assigning the value to the variable.


Syntax:

a = x++;

[Naheedmir]

++X is the prefix increment operator; this means that the value of x is first incremented and then used in the program. X++ is a postfix increment operator; this means that the value of x is first used in the program and then incremented. --x is prefixed decrement operator, this means that the value of x is first decremented and then used in the program. X-- is a postfix decrement operator, this means that the value of x is first used in the program and then decremented.

[AjayGohil]

Hi,

Preincrement take value and then increment.Post increment first increment and then take value

you can understand easily from below example.

open browser and run following piece of code in console.

var x=5;
//out put:undefined
var pre=++x;
//output:undefined
pre
//output:6
x
//output:6
var post=x++;
//output:undefined
post
//output:6