Header only and using modern C++ 17 and templates, provides a function enumerate that easily returns key-value pairs for any standard container type as seen in the Python programming language.
Tested on x86-64 gcc
Index values are always size_t. If you want the index, use that.
For map types that have a key, the resolved variable type needs to be that type.
See the comments in the code sample below
#include "Enumerate.h"
#include <iostream>
#include <vector>
#include <map>
#include <string>
int main(int argc, char** argv) {
std::vector<int> myVec({10,9,8,7,6,5,4,3,2,1});
// Capture index and value
for(const auto& [i, n] : enumerate(myVec)){
std::cout << "index: " << i << " value: " << n << std::endl;
// n is mutable
++n; // will increase all values in the list after printing
}
std::map<std::string, int> map{{"a", 10}, {"b", 9},{"c", 7}, {"d", 8}};
// Capture just the index
for(size_t index : enumerate(map)) {
// index for key-value pair as if it was sequential
std::cout << "index: " << index << std::endl;
}
// Capture just the key
for(std::string key : enumerate(map)) {
// the resolved value type has to be the same as the map's key type
std::cout << "key: " << key << std::endl;
}
// Capture the index and the items
for(const auto& [index, item] : enumerate(map)) {
// Decompose the item into keys and values
const auto& [key, value] = item;
std::cout << "index: " << index << " key: " << key << std::endl;
}
}