i++ and ++i operator

[anukalp]

What is the difference between ++i and ++i, both are increment, but i am confused with their operations.

any one kindly make me understand how they both works and what is the output, the output is same i have tried.

int main()
{   
   int x = 10;
   x++;
    printf("x is %d", x);
    return 0;
}

x is 11

and

int main()
{   
   int x = 10;
   ++x;
    printf("x is %d", x);
    return 0;
}

x is 11

 

[HellasTechn]

I know little about C language but i think that it is exactly the same thing.

 

[Hopup]

It is same thing in this context but it can be different thing when assigning variable for example.

 

[anukalp]

I know little about C language but i think that it is exactly the same thing.

I don't think Its same thing

it can be different thing when assigning variable for example.

Can you explain How its different ?

 

[Hopup]

It would cause different result in example like this:

A = 1;
B = ++A;

This results B = 2, A = 2

A = 1;
B = A++;

This results B = 1, A = 2

 

[(*steve*)]

If you study PDP-11 assembly language you'll see where many of C's features come from.

The addressing modes of auto increment/decrement, deferral, and indirection provide 1 instruction implementation of many of C's arithmetic and pointer operations for a certain set of variable types. The various flags set after arithmetic operations and the operation of the compare instruction provide further insight into aspects of the C language.

In many ways C reflects the desire to write low level code more easily on the PDP-11 predecesors and this closely reflects the architecture of this machine.

Many years ago, as a lark, I wrote a couple of macros for the PDP-11 assembler which translated a small subset of simple C statements into assembler.

The chicken and egg / pulling one's self up by the bootstraps implementation of the C compiler had it's early roots in something like this.

 

[Bluejets]

x++ gives value then increments
++x increments then gives value

 

[anukalp]

It would cause different result in example like this:

A = 1;
B = ++A;

This results B = 2, A = 2

A = 1;
B = A++;

This results B = 1, A = 2

This gives

int main(void)
{
   int a = 0;
   int b = a++;
 
   printf("Value of b is %d \n", b);
 
   printf("Value of a is %d \n",a);
 
   return 0;
}

Value of b is 0
Value of a is 1

and

int main(void)
{
   int a = 0;
   int b = ++a;
 
   printf("Value of b is %d \n", b);
 
   printf("Value of a is %d \n",a);
 
   return 0;
}

Value of b is 1
Value of a is 1

any reason When do you use ++a or a++ in program ?

 

[Hopup]

Like bluejets stated, it is about the order how the code is processed. Like you can see in my example, when the increment is before the A, it is processed but when its after it is not processed before the creation of new variable.