How to interfere other windows program (with C#, C++ or Java)

Sorry for the unclear title,but my english is not good enough to describes my question in one line.

For example, i have a udp gaming program called Garena,its halt user for 5s after every

attemp to join room (by some client-code i guess),therefor i downloaded another program which called Garena Auto-joiner(C++) ,this program bypass 5sec waiting and attemp to join room every second,ultil开发者_如何转开发 succeed.

For example Warcraft III do not have manabar show on top of heroes(nomally just have Hpbar),but when i download Manabar and run it after in game, it even render a manabar below Hpbar

What i want to ask is: "how can it do that?","is it related with cracking in anyway?","Can a Java program achieve similar use?".

Thank for your supports!

There's a lot of ways to interfer with other programs. For some samples:

• DLL Injection - using one of several methods
• Packet Injection - for networked programs
• Windows Debug API
• Code Injection - modifying the running program

This is usually done with C/C++ as their access to memory and other running processes is more straight forward. This is a good resource for understanding game hacking: cheat engine

The site's forum can provide more hands-on coding help.