C Language Programming Skills: C language "freehand" write memory

Source: Internet
Author: User
Tags printf

In the eyes of the application program ape, the C-language method of writing memory, as follows:

struct mystr * PTR;

ptr = malloc (sizeof (*PTR));

Ptr->filda= ' abc ';

ptr->fildb=89;

However, if it is a system program, no malloc, even need to design your own malloc, how to write memory?

Below for everyone to show a technology, this technology is more bloody and violent, not suitable for children.

Children over the age of 18 can continue to watch.

1 #include

2 #include

3

4 struct STR1 {

5 int i;

6 Char J;

7};

8

9 int main () {

struct str1 * PTR1;

One ptr1 = malloc (sizeof (*PTR1));

((int*) ptr1) = 23;

((char*) ((int*) PTR1 + 1)) = ' a ';

14

printf ("Now Ptr1->i Is:%dn", ptr1->i);

printf ("Now Ptr1->j Is:%dn", ptr1->j);

17

return 0;

19}

A daring little boy's shoes guess, ptr1->i is how much?

Yes, the output is this:

[Root@localhost ~]#./memwrite

Now Ptr1->i is:23

So, how much is ptr1->j?

If you know the answer, then why would he be the result?

If you haven't read it, add my QQ number.

If you understand the core principles of this hack, it's easy to read the Linux kernel's paging management, swap technology, etc.

Related Article

E-Commerce Solutions

Leverage the same tools powering the Alibaba Ecosystem

Learn more >

Apsara Conference 2019

The Rise of Data Intelligence, September 25th - 27th, Hangzhou, China

Learn more >

Alibaba Cloud Free Trial

Learn and experience the power of Alibaba Cloud with a free trial worth $300-1200 USD

Learn more >

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.