String to int in c++

Question

How to convert a string variable that consists of maximum 100 char to big int ?

My code:

 long long int x;
 string s="11111111111111111111111111111111";
 x=atoll(s.c_str());
 cout<<x;

Answer 1

You need to use a bignum library, like GNU MP aka GMP or libcrypto.

Since in a 64-bit environment most compiler use 64 bits for a long long int, you can't even reach near 100 decimal digits with a long long.