1.Generic code:
Reversibility principle says that write code in manner where you can use as much as you can and never ever reinvent the wheel ( never rewrite the code ). Not using generic code will result in redundant coding which means rewriting the lines again and again.
2.Methods :
1.Methods are again a nice way to use generic code.
2.Increase programming speed as many of languages methods uses cache memory.
3.Methods are called in stacks and thus uses less memory.
4. Structural programming is achieved by them.
