What are different standards of C language?

Question

I read in one of the articles about the evolution of C with different standards like C89, C99 and C11.
What are this standards?
Which is default standard used in general c programming?

Answer 1

I know only about C99,
it made to special upgrades in C. which are -

1) long long datatype after this upgrade you can use this datatype which is 8 byte size on 16 bit compiles, 16 byte in 32bit compiler and others.
it is used to store those integers which are not to long like
long long var = 13565568679643577536746776;

2) now you can declare counter variables inside loop also like
for (int k=0;k<=5;k++)
{
....
}

if you try it on old compiler like turbo C++, then it will generate error.

I hope you understand both.
and you know, that's the reason why our teacher using Turbo C++ to teach C/C++ . because works on original syntax of C program. modern compiler ignore it and they ignore generally.
header file declaration is generally ignored in modern compiles.

Answer 2

In C99 they added the primitif type _Bool with its values (_True and _False) which can be named bool, true and false if the header bool.h is included
They added _Complex and _Imaginary type with I as the purely imaginary number which square is -1
I think they also added other stuff but I did not went in deep enough to tell you