Title: A-Bomb dome in Hiroshima, Source: own resources, Authors: Agnieszka and Michał Komorowscy
When I returned to programming in C++ after years of using C# a few things were especially painful. Today I'll wrote about 2 at the top of the list. The first one was a need to explicitly declare types of local variables. For example:
std::vector< std::string > v = someMethod(); std::map< std::string, std::map<std::string, std::string> > m = someMethod2();It looks terrible and is simply cumbersome. However, as you may noticed I used the past tense. It turned out that it's not needed any more. Glory and honor to C++11!!! Now, I can write something like this.
auto v = someMethod(); auto m = someMethod2();The second problem was the lack of foreach operator. For example let's write a code that iterates through a map from the example above:
typedef std::map<std::string, std::map<std::string, std::string>>::iterator outer_iterator;
typedef std::map<std::string, std::string>::iterator inner_iterator;
for(outer_iterator it1 = m.begin(); it1 != m.end(); it1++) {
for(inner_iterator it2 = it1->second.begin(); it2 != it1->second.end(); it2++) {
std::cout<< it1->first << " " << it2->first << " " << it2->second << std::endl;
}
}
Again it looks terrible and is cumbersome. All this begin(), end(), typedef are horrible. We can fix it a little bit if we use auto keyword:
for(auto it1 = m.begin(); it1 != m.end(); it1++) {
for(auto it2 = it1->second.begin(); it2 != it1->second.end(); it2++) {
std::cout<< it1->first << " " << it2->first << " " << it2->second << std::endl;
}
}
But even the better result we will achieve if we use a new for loop syntax:
for(auto it1 : m) {
for(auto it2 : it1.second) {
std::cout<< it1.first << " " << it2.first << " " << it2.second << std::endl;
}
}
The difference is striking! It's so much readable and easier to write and uderstand.
orcid.org/0000-0002-6838-2135