Auto comment: topic has been updated by beginner1010 (previous revision, new revision, compare).

Not as cool, but I use simple

#define watch(x) cout << (#x) << " is " << (x) << endl

to debug single variables

void debug_out(vector<string> __attribute__ ((unused)) args, __attribute__ ((unused)) int idx) { cerr << endl; }

to get rid of the compiler warnings caused by -Wunused-parameter

Auto comment: topic has been updated by beginner1010 (previous revision, new revision, compare).

Can we do some modification in above template so that we can also print STl containers like map, vector, set, multiset (also map<pair<int,pair<int,int>>, int> type things).

This snippet is not printing anything on the console in my PC....No errors, no warnings although... What should I do??

Please help me out!!

Here is a function for print any stl container that has begin() and end():

template<typename C, 
         typename T = std::decay_t<decltype(*begin(std::declval<C>()))>,
         typename std::enable_if<!std::is_same<C, std::string>::value>::type* = nullptr
         >
std::ostream &operator<<(std::ostream &os, const C &container){
  bool first = true;
  std::stringstream ss; 
  ss << '[';
  for(const auto &x : container){
    if (!first){
      ss << ", ";
    }
    first = false;
    ss << x;
  }
  ss << ']';
  return os << ss.str();
}

Example:

vector<int> vec{1,2,3,4,5,6};
cout << vec << endl;
set<int> s{3,4,5,6};
cout << s << endl;
//Output
//[1, 2, 3, 4, 5, 6]
//[3, 4, 5, 6]

Work for map too if you overload operator<< for pair

template<class T1, class T2>
std::ostream &operator<<(std::ostream &os, const std::pair<T1,T2> &p){
  os << '{' << p.first << ", " << p.second << '}';
  return os;
}

//
map<int,string> m = {
 {1, "awesome"},
 {2, "c++"}
};
cout << m << endl;
//[{1, awesome}, {2, c++}]
map<pair<int,int>,pair<bool,float>> m2 = {
 {{1, 2}, {true, 3.0}},
 {{3, 4}, {false, 9.f}}
};
cout << m2 << endl;
//[{{1, 2}, {1, 3}}, {{3, 4}, {0, 9}}]

#ifdef XOX
#define debug(...) debug_out(vec_splitter(#__VA_ARGS__), 0, __LINE__, __VA_ARGS__)
#else
#define debug(...) 42
#endif

Here what is meant by

#define debug(...) 42 ???

Why we defined 42 as debug(...)?

Hello,

When I do:

int test[10] = {0};
debug(test);

He sends me back:

test = 0x7fffed0acd20

How can I display all my board on the line instead of its address?

Thank you

To support STL containers and line number

#include <bits/stdc++.h>
using namespace std;
/// ----------------------------- (Debug) ------------------------------
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; }; sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0); sim > char dud(...);
struct debug {
#ifdef LOCAL
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i));}
sim, class b dor(pair < b, c > d) {ris << "(" << d.first << ", " << d.second << ")";}
sim dor(rge<c> d) {*this << "["; for (auto it = d.b; it != d.e; ++it) *this << ", " + 2 * (it == d.b) << *it; ris << "]";}
#else
sim dor(const c&) { ris; }
#endif
};
vector<char*> tokenizer(const char* args) {
    char *token = new char[111]; strcpy(token, args); token = strtok(token, ", ");
    vector<char*> v({token});
    while(token = strtok(NULL,", ")) v.push_back(token);
    return reverse(v.begin(), v.end()), v;
}
void debugg(vector<char*> args) { cerr << "\b\b "; }
template <typename Head, typename... Tail>
void debugg(vector<char*> args, Head H, Tail... T) {
    debug() << " [" << args.back() << ": " << H << "] ";
    args.pop_back(); debugg(args, T...);
}
#define harg(...) #__VA_ARGS__
#ifdef LOCAL
#define dbg(...) { debugg(tokenizer(harg(__VA_ARGS__, \b\t-->Line)), __VA_ARGS__, __LINE__); cerr << endl;}
#else
#define dbg(...) { }
#endif
/// -----------------------------------------------------------------------

int main() {
    vector<int> v({1, 2, 3});
    map<int, int> mp;
    int x =10;
    int y =11;
    mp[12] = 13;
    dbg(x, y, v, mp);

    return 0;
}

just add -D LOCAL flag

how can I print the debug output to a file? currently it prints to terminal

Unfortunately this doesn't work when you debug a function call with more than one argument because the commas trick the vec splitter. Guess I'll go back to my not so cool

#define debug(x) cerr << "Line " << __LINE__ << ": " << #x << " = " << to_string(x) << endl

I copy and paste your code but it doesn't print anything.

Don't forget to use passing by reference (avoid unnecessary copying):

...
void debug_out(const vector<string>& args, int idx, int LINE_NUM, const Head& H, const Tail&... T) {
...

One stop to debug template and its usage:

https://cs-mshah.github.io/getting_started_with_cp/#debugging

I used something similar myself, except one day I was bored so I decided to add the functionality to print stuff in different colors lol. It's hardly the most useful feature but does help sometimes with large implementations

The output —

(Don't judge my code too hard, it's a big steaming pile of mess but I don't have to look at it so I never bother to fix it lol)

If you choose to use it, I recommend you turn word wrap off

#define GREEN "\033[1;32m"
#define YELLOW "\033[1;33m"
#define ORANGE "\033[1;34m"
#define PURPLE "\033[1;35m"
#define BLUE "\033[1;36m"
#define trace(...) __f(__LINE__,YELLOW,#__VA_ARGS__, __VA_ARGS__)
#define Trace(color,...) __f(__LINE__,color,#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(int line, const char *color, const char* name, Arg1&& arg1){
        cerr << "\033[2;37m(Ln " << line << ")\033[0m " << color << name << ": \033[0;37m" << arg1 << "\033[0m " << endl;
    }
    template <typename Arg1, typename... Args>
    void __f(int line, const char *color, const char* names, Arg1&& arg1, Args&&... args){
        const char* comma = strchr(names + 1, ',');
        cerr << "\033[2;37m(Ln " << line << ")\033[0m " << color;
        cerr.write(names, comma - names) << ": \033[0;37m" << arg1 << "\033[0m " << endl;
        __f(line,color, comma+1, args...);
    }

//IO operators for vectors, pairs, sets, maps and __int128 so I can print just about anything
template <typename T>istream &operator>>(istream &in, vector<T> &v){for (auto &i : v)in >> i;return in;}
template <typename T>ostream &operator<<(ostream &ost, vector<T> v){if(&ost == &cerr){cerr <<"{";int cnt = v.size();for(auto x:v){cerr << x;cnt--;if(cnt) cerr << ", ";}cerr << "}";}else for(auto i:v)ost << i << " ";return ost;}
template <typename T>ostream &operator<<(ostream &ost, set<T> s){if(&ost == &cerr){cerr <<"{";int cnt = s.size();for(auto x:s){cerr << x;cnt--;if(cnt) cerr << ", ";}cerr << "}";}else for(auto i:s)ost << i << " ";return ost;}
template <typename T>ostream &operator<<(ostream &ost, multiset<T> s){if(&ost == &cerr){cerr <<"{";int cnt = s.size();for(auto x:s){cerr << x;cnt--;if(cnt) cerr << ", ";}cerr << "}";}else for(auto i:s)ost << i << " ";return ost;}
template <typename U, typename V>ostream &operator<<(ostream &ost, map<U,V> &m){if(&ost == &cerr){cerr <<"{";int cnt = m.size();for(auto x:m){cerr << x; cnt--;if(cnt) cerr << ", ";}cerr << "}";}else for(auto i:m)ost << i;return ost;}
template <typename U, typename V>istream &operator>>(istream &in, pair<U, V> &p){in>>p.first>>p.second;return in;}
template <typename U, typename V>ostream &operator<<(ostream &ost, pair<U, V> p){if (&ost == &cerr)ost << "{" << p.first << ": " << p.second << "}";else ost << p.first << " " << p.second << " ";return ost;}
ostream &operator<<(ostream &ost, __int128_t x){string output = "";while(x)output += '0'+x%10, x /= 10;reverse(all(output)); ost << output;  return ost;}
istream &operator>>(istream &in, __int128_t &x){x=0;string num;cin >> num;for(char c:num) x *= 10, x += c-'0';return in;}
//Variadic IO
template <typename... T>void read(T &...args){((cin >> args), ...);}
template <typename... T>void print(T... args){((cout << args << " "), ...);cout << endl;}

void solve()
{
    vector<int> v = {1,2,3};
    int a = 2;
    map<int,int> m;
    m[5] = 3;
    m[4] = 2;
    m[1] = 7;
    trace(v,a,m);
    Trace(ORANGE,v,a,m);
}