Debugging the traditional way

Ever wanted to look in console at variables you use? Meet three helper functions!

dbg()

Suppose we have some nested containers(vector, string, bitset, set, map) or arrays, which for simplicity we may consider a multidimensional array with some dimensions. dbg() can neatly print the name, bounds and, at last, the values from the required sub-array with automatic bound checking:

For example:

    int j[2][2][3] = {{{4,5,6},{10,11,12}}, {{1,2,3}, {7,8,9}}};
    dbg(j, 0,0, 0,1, 0,1);

To do so, you pass the name of array and [two closed bounds] for each dimension(btw, you can omit several last bounds). If they are too large, dbg() reduces them so that they are inside the arr. By default the bounds are set on the start and the end of each dimension.

ATTENTION!

++If you pass bounds [l;r] to the dimension that is map or set, the output goes from the lth largest key to the rth largest, or to the last element of dimension(if r is too big).

++dbg() works with c-arrays whose sizes of dimensions are constant and are known at compile time.

const int N = 3, M = 2;
int main(){
    for(int i = 0; i < 4; ++i){
        char b[3][2] = {'p','q','r','s'};
        dbg(b);
    }
}

int main(){
    for(int i = 0; i < 4; ++i){
        char b[3][2] = {'p','q','r','s'};
        dbg(b);
    }
}

++If you set the incorrect bounds, the empty lines instead of values of container are printed.

/*-----------------------------------------------*/

Let's look at the container's elements from 1st to 2nd

    map<vector<int>, vector<string>> a = {{{3,4},{"sauron"}}, {{1,2},{"gandalf", "the", "gray"}}, {{5},{"frodo","bilbo"}}};
    
    // traditional version
    auto l = begin(a), r = begin(a);
    advance(l,1), advance(r, min(int(a.size()), 3));
    for(; l != r; ++l){
        cout << "{"; for(auto &ff : (*l).first) cout << ff << ","; cout << "}";
        cout << "{"; for(auto &ff : (*l).second) cout << ff << ","; cout << "}\n";
    } cout << "\n";
    
// output: 
{3,4,}{sauron,}
{5,}{frodo,bilbo,}

    // dbg():
    dbg(a,1,2);

// output:
[a,1,2]: 
[([3, 4], ["sauron"]), ([5], ["frodo", "bilbo"])]

/*-----------------------------------------------*/

Let's print some variables

    int t = 5; char u = 'R';
    pair<pair<double, unsigned int>, pair<int, string>> v = {{234.34534, 42}, {133, "IOI"}};
    
    // traditional version:
    #define fi first
    #define se second
    cout << t << " | " << u << " | " << "{ { " << v.fi.fi << "," << v.fi.se << " }{ " << v.se.fi << "," << v.se.se << " } }\n"; 
    
// output:
5 | R | { { 234.345,42 }{ 133,IOI } }


    // dbg
    dbg(t), dbg(u), dbg(v);
   
// output
[t]: 5

[u]: R

[v]: ((234.345340,42),(133,"IOI"))
    

/*-----------------------------------------------*/

Here's my code. It's hugely inspired by this submission by tourist.

The compact version is created from the extended one by means of http://removelinebreaks.net/.

/*-----------------------------------------------*/

Hope these functions save your precious minutes during contests. Enjoy!

UPD: egregious bug with bitsets fixed