manipulating c variable via inline assembly

> **Possible Duplicate:**
> [How to access c variable for inline assembly manipulation](

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Given this code:

#include <stdio.h>

int main(int argc, char **argv)
{
int x = 1;
printf("Hello x = %d\n", x);


}

I'd like to access and manipulate the variable x in inline assembly. Ideally, I want to change its value using inline assembly. GNU assembler, and using the AT&T syntax. Suppose I want to change the value of x to 11, right after the printf statement, how would I go by doing this?

The `asm()` function follows this order:

asm ( "assembly code"
: output operands /* optional */
: input operands /* optional */
: list of clobbered registers /* optional */
);

and to put 11 to x with assembly via your c code:

int main()
{
int x = 1;

asm ("movl %1, %%eax;"
"movl %%eax, %0;"
:"=r"(x) /* x is output operand and it's related to %0 */
:"r"(11) /* 11 is input operand and it's related to %1 */
:"%eax"); /* %eax is clobbered register */

printf("Hello x = %d\n", x);
}

You can simplify the above asm code by avoiding the clobbered register

asm ("movl %1, %0;"
:"=r"(x) /* related to %0*/
:"r"(11) /* related to %1*/
:);

You can simplify more by avoiding the input operand and by using local constant value from asm instead from c:

asm ("movl $11, %0;" /* $11 is the value 11 to assign to %0 (related to x)*/
:"=r"(x) /* %0 is related x */
:
:);

Another example:

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