#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); whats this mean??why ios???

[namans...@gmail.com]

#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

#define endl "\n"

#define ll long long

#define pb push_back

#define mp make_pair

#define fi first

#define se second

int32_t main()

{

    IOS;

    int n,c;

    cin>>n>>c;

    .

     .

    . 

     .

  }

ios mean here?????? and int 32_t mean???

[zoso]

IOS is a macro. Macros are simple text expansions. As in the above example, you can see that there's the line

#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

So when it's used in

int32_t main() {

IOS;

that IOS is just substituted with the #define IOS expansion and it shall thus become:

int32_t main() {

ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);;

The 'ios' in ios::sync_with_stdio is a class in the <ios> header file of C++ library. (https://en.cppreference.com/w/cpp/io/ios_base)

Now coming to the other half. int32_t is a "fixed-width" integer type defined in <cstdint> header file. You would've normally seen 'int a = 5;' being used. One problem with that statement is that there's no guarantee as to what would be the size of 'int' on various platforms. It can be 2 bytes (16 bits) or 4 bytes (32 bits) depending on what Operating System one is executing the program on. To avoid this uncertainty. one can use fixed-width integer types like int32_t which indicates that irrespective of the platform, that variable will always be of 32-bits (or 4 bytes).