how to store the size of string which has size 99999999999999 into a variable like :data_type x=sizeof(s); where s is stringname

Answer 1

it is nearly impossible to to have a single string with this much of size.
if you try to do that your program will crash.
max big size of string is 16380
by this site
https://msdn.microsoft.com/en-us/library/dddywwsc(VS.80).aspx
solution
multidimensional array , each.line new array.
or save parts of string in file.

Answer 2

use string::size_type var; var=sizeof(s); this can be used to store any large amount of size