Why does c++ have type modifiers?

Answer 1

C++ Modifier Types. C++ allows the char, int, and double data types to have modifiers preceding them. A modifier is used to alter the meaning of the base type so that it more precisely fits the needs of various situations. The modifiers signed, unsigned, long, and short can be applied to integer base types.
https://www.tutorialspoint.com/cplusplus/cpp_modifier_types.htm

Answer 2

bcause,
modifiers gives the data types more memory to keep values

signed, unsigned, short , long

example
_------------_

if 16 bits gives to int
signed int gives 32 bits

so it doubles

unsigned int gives -16
to +16 bits