How Can I Elegantly Initialize Vectors in C ?

Simplifying Vector Initialization: Elegant Hardcoding Options

Creating custom initializers for arrays is a standard and straightforward practice. However, when it comes to vectors, finding a similar mechanism can be a bit trickier. The inherent question is whether there exists a method to initialize vectors as cleanly as arrays. Let's explore the solutions.

The standard approach, as you mentioned, involves push_back operations:

std::vector<int> ints;
ints.push_back(10);
ints.push_back(20);
ints.push_back(30);

While this method serves its purpose, it doesn't match the elegance of array initialization.

C 11's Brace-Enclosed Initialization

With C 11 and compatible compilers like GCC 4.4, you can embrace brace-enclosed initialization for vectors:

std::vector<int> v = {1, 2, 3, 4};

This syntax provides a concise and explicit way to initialize vectors.

Boost.Assign Library

Another alternative is to utilize the Boost.Assign library. It offers various techniques for vector initialization:

Using list_of:

#include <boost/assign/list_of.hpp>
...
std::vector<int> v = boost::assign::list_of(1)(2)(3)(4);

Using = notation:

#include <boost/assign/std/vector.hpp>
using namespace boost::assign;
...
std::vector<int> v;
v += 1, 2, 3, 4;

However, note that Boost.Assign carries some performance overhead due to its underlying mechanisms. For performance-sensitive code, consider the push_back approach.

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