lexicographic

If I have a class that I want to be able to sort (ie support a less-than concept), and it has several data items such that I need to do lexicographic ordering then I need something like this: struct MyData { string surname; string forename; bool operator<(const MyData& other) const { return surname < other.surname || (surname==other.surname && forename < other.forename); } }; This becomes pretty unmanageable for anything with more than 2 data members. Are there any simpler ways of achieving it? The data members may be any Comparable class. tuple is a good idea, but if you want to keep having

I have a list which contains strings representing animal names. I need to sort the list. If I use sorted(list) , it will give the list output with uppercase strings first and then lowercase. But I need the below output. Input: var = ['ant','bat','cat','Bat','Lion','Goat','Cat','Ant'] Output: ['ant', 'Ant', 'bat', 'Bat', 'cat', 'Cat', 'Goat', 'Lion'] The sort() method and the sorted() function take a key argument: var.sort(key=lambda v: v.upper()) The function named in key is called for each value and the return value is used when sorting, without affecting the actual values: >>> var=['ant',

I know that when we are using template inside another template, we should write it like this: vector<pair<int,int> > s; and if we write it without the whitespace: vector<pair<int,int>> s; we will get an error: `>>' should be `> >' within a nested template argument list I see this is understandable, but I just can't help but wondering, in which cases will this be really ambiguous? Sometimes you want it to be >> . Consider boost::array<int, 1024>>2> x; In C++03 this successfully parses and creates an array of size 256 . It won't ever be ambiguous. This is proven by the fact that in C++0x you don

I was curious how std:next_permutation was implemented so I extracted the the gnu libstdc++ 4.7 version and sanitized the identifiers and formatting to produce the following demo... #include <vector> #include <iostream> #include <algorithm> using namespace std; template<typename It> bool next_permutation(It begin, It end) { if (begin == end) return false; It i = begin; ++i; if (i == end) return false; i = end; --i; while (true) { It j = i; --i; if (*i < *j) { It k = end; while (!(*i < *--k)) /* pass */; iter_swap(i, k); reverse(j, end); return true; } if (i == begin) { reverse(begin, end);

What does "compare two strings lexicographically" mean? Leading from answers from @Bozho and @aioobe, lexicographic comparisons are similar to the ordering that one might find in a dictionary. The Java String class provides the .compareTo () method in order to lexicographically compare Strings. It is used like this "apple".compareTo ("banana") . The return of this method is an int which can be interpreted as follows: returns < 0 then the String calling the method is lexicographically first (comes first in a dictionary) returns == 0 then the two strings are lexicographically equivalent returns