This is the list of modern CPP tricks often used in Coding Interviews and Competitive Programming.
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pair<int, int> cur = {1, 2};
auto [x, y] = cur;
// x is now 1, y is now 2
// no need of cur.first and cur.second
array<int, 3> arr = {1, 0, -1};
auto [a, b, c] = arr;
// a is now 1, b is now 0, c is now -1
Straight to the point, I have often used the debug
macro which stringifies the variable names and their values.
#define deb(x) cout << #x << " " << x
int ten = 10;
deb(ten); // prints "ten = 10"
This is often useful in debugging.
However, when you have multiple variables to log, you end up with more deb2
and deb3
macros.
#define deb(x) cout << #x << " " << x
#define deb2(x) cout << #x << " " << x << " " << #y << " " << y
#define deb3(x, y, z) cout << #x << " " << x << " " << #y << " " << y << " " << #z << " " << z
This is not scalable.
Here is the solution using variadic macros and fold expressions,
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
cout << vars << " = ";
string delim = "";
(..., (cout << delim << values, delim = ", "));
}
int xx = 3, yy = 10, xxyy = 103;
deb(xx); // prints "xx = 3"
deb(xx, yy, xxyy); // prints "xx, yy, xxyy = 3, 10, 103"