What general tips do you have for golfing in C++?
I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to C++ (e.g. "remove comments" is not an answer). Please post one tip per answer.
(Tips that apply to C as well can be found in Tips for golfing in C - but note that some C tips don't work in C++. For example, C++ does require function prototypes and return values.)
From C++11, a std::string is always zero-terminated. Thus, of all the characters, exactly the last one is falsy. So, these loops are equivalent:
#include<string> std::string s; // indexed loop, yielding an index // ungolfed for(int i = 0; i < s.size(); i++) { std::cout << s[i]; } // golfed C++98 for(int i=0;i++<s.size();)std::cout<<s[i]; // golfed C++11 for(int i=0;s[i++];)std::cout<<s[i]; Note, that depending on the surrounding code, the following alternative looping techniques may be more efficient:
// C++11 iterator loop, yielding an iterator for(auto i=s.begin();i++<s.end();)std::cout<<*i; // C++11 ranged-for loop, yielding a character for(auto c:s)std::cout<<c; The latter work likewise for std::vector.
for(auto i=s.begin();i<s.end();i++) consider for(auto i=begin(s);i<end(s);i++) or for(auto i=&s[0];i<&*end(s);i++) if your container supports them. \$\endgroup\$ using namespace std;. \$\endgroup\$ Don't use string(""), use "". It saves 8 bytes.
"" + 'a' is char* + char, which is pointer addition, while std::string("") + 'a' is std::string + char - string concatenation. string() would work. \$\endgroup\$ ""s. This saves 7 bytes and still is a std::string. \$\endgroup\$ using namespace std::literals to use ""s \$\endgroup\$