UD chains and DU chains in all languages .

i am in the way of failure , but  i am sure that i will succeed in my task which i set for me and myself . when you get or feel something bad , that you are going in the shrink , i think that is the phase where you have to start . this topic looks too complicated but it is too easy to understand .

we have two things UD chains and DU chains .

UD chains :--
                     UD is a combination of two things . 1st is U and another is D . the meaning of  "U" is that a variable and the meaning of "D" is all the definitions of the variable but now what is the sense of meaning .
look at this
declare a variable :---- int a ;
a = 10 ; 
a = 20 ;
a = x+y ;
there are 3 different use of a single "a" variable .


DU chains :--
                     DU is a combination of two things . 1st is D and another is U . the meaning of "D" is definition and u means use of this definition ..
look at this
declare a variable :---- int a = 5 ;
int x = a ;
int y = x + a ;
two different use of  a definition .

use of DU and UD is in , data linking , sign extension algorithms .