Garbage Value: If any variable is not initialized then that variables having garbage value(unassigned value). For example: int i; Variable ‘i’ is integer type but it wont assign any value.so,it take garbage value.It maybe any value. Before allocating memory in run time system does not clear the memory before allocating the variable.So,default value of the variable is garbage value.

1. Calculating garbage
value in case of Overflow

2. Garbage value in C
 In a language like C, when you define a variable, like:
int x;
 A small block of memory is allocated to the variable. However, we
have only declared the variable, and not initialized it, which means
that the block of memory that has been allocated to the variable still
contains some value that has been left over from previous programs
and operations. That value is called a garbage value. This may lead
to erroneous results in programs.
 To avoid this, declare and initialize variables like this:
int x = 0;

3. In case of Windows
 The space allocated for a variable of int datatype is 16 bits.
 That means the maximum negative value that can be stored by the
variable of int datatype is 2^15=-32768.
 You may ask why 2^15 not 2^16.
 This is because one bit is reserved for sign(+ or -)
 Similarly the maximum +ve value that a variable of int datatype can
store is 2^15-1=32767.
 Why -1.Because 0 is also counted in case of +ve values.

4.  Now lets come to long datatype.
 The space allocated for a variable of int datatype is 32 bits.
Maximum negative value= 2^31= -2147483648
Maximum +ve value= 2^31-1=2147483647
 The space allocated for a variable of long datatype is 64 bits.
Maximum negative value= 2^63= -9.22337e+18
Maximum +ve value= (2^63)-1= 9.22337e+18

5. Formula for calculating garbage value
garbage value=overflow value-reference value.
reference value is the value such that it is greater than the
overflow value(neglecting the sign)
obtained by the multiplication of the basic reference value by 2
until the value is greater than the overflow value(neglecting the
sign)
The sign of the reference value is same as that of overflow
value.
Basic reference value is 2^n where n represents the number of
bits allocated.
The garbage value thus calculated is checked whether it can fit
the variable or not. If not the steps are repeated again.

6. Basic reference value=32768
since the reference value is less than the overflow value
,we have to multiply it by 2
i.e,32768*2=65536
65536 is greater than the 45000.That means reference
value(RV)=65536.SInce RV must be of same
sign,RV=+65536
1. now apply formula
2. garbage value=overflow value-reference value.
3. garbage value=45000-(+65536)
4. garbage value=-20536
5. -20536 comes within the limits of int datatype.

7. Lets understand what happens.
That means.
OV=32768 Basic RV=32768.
RV must be greater than OV.
Therfore RV=32768*2=65536
Now, garbage value(GV)=OV-RV=32768-65536=-32768

8. Since both variables a
and b are assigned a
value greater than their
limits, when you run this
program some garbage
value will be the output.

9. 2^31
RV>OV