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c++if-statementc++17initializer

C++ new if statement with initializer


The cppreference page for "if" statement;

https://en.cppreference.com/w/cpp/language/if

gives the following example;

Except that names declared by the init-statement (if init-statement is a declaration) and names declared by condition (if condition is a declaration) are in the same scope, which is also the scope of both statements Blockquote

std::map<int, std::string> m;
if (auto it = m.find(10); it != m.end()) { return it->size(); }

Thats a typo, isn't it? I'm not missing anything here am I, it should be;

it->second.size(); 

or

it->first;

No?


Solution

  • Yes, this is a typo. iterator for std::map will be dereferenced as std::map::value_type, where value_type is std::pair<const Key, T>.

    See example of usage for std::map::find (from cppreference):

    #include <iostream>
    #include <map>
    int main()
    {  
        std::map<int,char> example = {{1,'a'},{2,'b'}};
    
        auto search = example.find(2);
        if (search != example.end()) {
            std::cout << "Found " << search->first << " " << search->second << '\n';
        } else {
            std::cout << "Not found\n";
        }
    }