用硬编码元素初始化std :: vector的最简单方法是什么？

#1 楼

static const int arr[] = {16,2,77,29};
vector<int> vec (arr, arr + sizeof(arr) / sizeof(arr[0]) );

#2 楼

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

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

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

#3 楼

std::vector<int> vec = {10,20,30};

#4 楼

int tmp[] = { 10, 20, 30 };
std::vector<int> v( tmp, tmp+3 ); // use some utility to avoid hardcoding the size here

vector<int> v = list_of(10)(20)(30);

// option 1, typesafe, not a compile time constant
template <typename T, std::size_t N>
inline std::size_t size_of_array( T (&)[N] ) {
   return N;
}
// option 2, not typesafe, compile time constant
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))

// option 3, typesafe, compile time constant
template <typename T, std::size_t N>
char (&sizeof_array( T(&)[N] ))[N];    // declared, undefined
#define ARRAY_SIZE(x) sizeof(sizeof_array(x))

#5 楼

#include <vector>
using std::vector;
...
vector<int> vec1 { 10, 20, 30 };
// or
vector<int> vec2 = { 10, 20, 30 };

#include <vector>
#include <boost/assign/list_of.hpp>
using std::vector;
...
vector<int> vec = boost::assign::list_of(10)(20)(30);

#include <vector>
#include <boost/assign/std/vector.hpp>
using std::vector;
...
vector<int> vec;
vec += 10, 20, 30;

#include <vector>
using std::vector;
...
static const int arr[] = {10,20,30};
vector<int> vec (arr, arr + sizeof(arr) / sizeof(arr[0]) );

#include <vector>
#define ARRAY_SIZE(ar) (sizeof(ar) / sizeof(ar[0])
#define ARRAY_END(ar) (ar + ARRAY_SIZE(ar))
using std::vector;
...
static const int arr[] = {10,20,30};
vector<int> vec (arr, ARRAY_END(arr));

#include <vector>
#define INIT_FROM_ARRAY(ar) (ar, ar + sizeof(ar) / sizeof(ar[0])
using std::vector;
...
static const int arr[] = {10,20,30};
vector<int> vec INIT_FROM_ARRAY(arr);

#6 楼

template< typename T, size_t N >
std::vector<T> makeVector( const T (&data)[N] )
{
    return std::vector<T>(data, data+N);
}

const double values[] = { 2.0, 1.0, 42.0, -7 };
std::vector<double> array = makeVector(values);

#7 楼

vector<int> v(arr, arr + sizeof(arr)/sizeof(arr[0]));
vector<int>v;

 v.push_back(SomeValue);

vector<int>v = {1, 3, 5, 7};

#8 楼

int a[] = {10, 20, 30}; //i'm assuming a is just a placeholder

const int a[] = {10, 20, 30};
const std::vector<int> ints(a,a+sizeof(a)/sizeof(int)); //make it const if you can

#include <boost/assign.hpp>
const std::vector<int> ints = boost::assign::list_of(10)(20)(30);

const std::vector<int> ints = {10,20,30};

#9 楼

vector<int> v = {10,20,30}

int array[] = {10,20,30}
for(unsigned int i=0; i<sizeof(array)/sizeof(array[0]); i++)
{
     v.push_back(array[i]);
}

#10 楼

vector<int> ints = {10, 20, 30};

#11 楼

#include <cstdarg>
#include <iostream>
#include <vector>

template <typename T>
std::vector<T> initVector (int len, ...)
{
  std::vector<T> v;
  va_list vl;
  va_start(vl, len);
  for (int i = 0; i < len; ++i)
    v.push_back(va_arg(vl, T));
  va_end(vl);
  return v;
}

int main ()
{
  std::vector<int> v = initVector<int> (7,702,422,631,834,892,104,772);
  for (std::vector<int>::const_iterator it = v.begin() ; it != v.end(); ++it)
    std::cout << *it << std::endl;
  return 0;
}

#12 楼

#define INIT_VECTOR(type, name, ...) \
static const type name##_a[] = __VA_ARGS__; \
vector<type> name(name##_a, name##_a + sizeof(name##_a) / sizeof(*name##_a))

INIT_VECTOR(int, my_vector, {1, 2, 3, 4});

#13 楼

std::vector<int> v;
v+=1,2,3,4,5;

template <class T> class vector_inserter{
public:
    std::vector<T>& v;
    vector_inserter(std::vector<T>& v):v(v){}
    vector_inserter& operator,(const T& val){v.push_back(val);return *this;}
};
template <class T> vector_inserter<T> operator+=(std::vector<T>& v,const T& x){
    return vector_inserter<T>(v),x;
}

#14 楼

static const int a[] = {10, 20, 30};
vector<int> vec (begin(a), end(a));

#15 楼

vector<int> values;  
values += 1,2,3,4,5,6,7,8,9;

#16 楼

// Based on answer by "Viktor Sehr" on Stack Overflow
// https://stackoverflow.com/a/8907356
//
template <typename T>
class mkvec {
public:
    typedef mkvec<T> my_type;
    my_type& operator<< (const T& val) {
        data_.push_back(val);
        return *this;
    }
    my_type& operator<< (const std::vector<T>& inVector) {
        this->data_.reserve(this->data_.size() + inVector.size());
        this->data_.insert(this->data_.end(), inVector.begin(), inVector.end());
        return *this;
    }
    operator std::vector<T>() const {
        return data_;
    }
private:
    std::vector<T> data_;
};

std::vector<int32_t>    vec1;
std::vector<int32_t>    vec2;

vec1 = mkvec<int32_t>() << 5 << 8 << 19 << 79;  
// vec1 = (5,8,19,79)
vec2 = mkvec<int32_t>() << 1 << 2 << 3 << vec1 << 10 << 11 << 12;  
// vec2 = (1,2,3,5,8,19,79,10,11,12)

#17 楼

#18 楼

class MyObject;

struct MyObjectList
{
    std::list<MyObject> objects;
    MyObjectList& operator<<( const MyObject o )
    { 
        objects.push_back( o );
        return *this; 
    }
};

someFunc( MyObjectList &objects );

someFunc( MyObjectList() << MyObject(1) <<  MyObject(2) <<  MyObject(3) );

#19 楼

template<class T>
class make_vector {
    std::vector<T> data;
public:
    make_vector(T const &val) { 
        data.push_back(val);
    }

    make_vector<T> &operator,(T const &t) {
        data.push_back(t);
        return *this;
    }

    operator std::vector<T>() { return data; }
};

template<class T> 
make_vector<T> makeVect(T const &t) { 
    return make_vector<T>(t);
}

#20 楼

typedef std::vector<int> arr;

arr a {10, 20, 30};       // This would be how you initialize while defining

clang++ -std=c++11 -stdlib=libc++  <filename.cpp>

#21 楼

// Before C++11
// I used following methods:

// 1.
int A[] = {10, 20, 30};                              // original array A

unsigned sizeOfA = sizeof(A)/sizeof(A[0]);           // calculate the number of elements

                                                     // declare vector vArrayA,
std::vector<int> vArrayA(sizeOfA);                   // make room for all
                                                     // array A integers
                                                     // and initialize them to 0 

for(unsigned i=0; i<sizeOfA; i++)
    vArrayA[i] = A[i];                               // initialize vector vArrayA


//2.
int B[] = {40, 50, 60, 70};                          // original array B

std::vector<int> vArrayB;                            // declare vector vArrayB
for (unsigned i=0; i<sizeof(B)/sizeof(B[0]); i++)
    vArrayB.push_back(B[i]);                         // initialize vArrayB

//3.
int C[] = {1, 2, 3, 4};                              // original array C

std::vector<int> vArrayC;                            // create an empty vector vArrayC
vArrayC.resize(sizeof(C)/sizeof(C[0]));              // enlarging the number of 
                                                     // contained elements
for (unsigned i=0; i<sizeof(C)/sizeof(C[0]); i++)
     vArrayC.at(i) = C[i];                           // initialize vArrayC


// A Note:
// Above methods will work well for complex arrays
// with structures as its elements.

#22 楼

int arr[] = {1, 2, 3};
int len = (sizeof(arr)/sizeof(arr[0])); // finding length of array
vector < int > v;
std:: v.assign(arr, arr+len); // assigning elements from array to vector 

#23 楼

 assert(MyFunction() == std::vector<int>{1, 3, 4}); // <- this.
 

#24 楼

// Create an empty vector 
    vector<int> vect;  

    vect.push_back(10); 
    vect.push_back(20); 
    vect.push_back(30); 

vector<int> vect{ 10, 20, 30 };

    int arr[] = { 10, 20, 30 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 

    vector<int> vect(arr, arr + n); 

    vector<int> vect1{ 10, 20, 30 }; 

    vector<int> vect2(vect1.begin(), vect1.end()); 

#25 楼

#define VECTOR(first,...) \
   ([](){ \
   static const decltype(first) arr[] = { first,__VA_ARGS__ }; \
   std::vector<decltype(first)> ret(arr, arr + sizeof(arr) / sizeof(*arr)); \
   return ret;})()

template<typename T>
void test(std::vector<T>& values)
{
    for(T value : values)
        std::cout<<value<<std::endl;
}

test(VECTOR(1.2f,2,3,4,5,6));

#26 楼

#27 楼

// Initializing a vector that holds 2 elements of type int.
Initializing:
std::vector<int> ivec = {10, 20};


// The push_back function is more of a form of assignment with the exception of course
//that it doesn't obliterate the value of the object it's being called on.
Assigning
ivec.push_back(30);

#28 楼

#include <initializer_list>
Vector<Type>::Vector(std::initializer_list<Type> init_list) : _size(init_list.size()),
_capacity(_size),
_data(new Type[_size])
{
    int idx = 0;
    for (auto it = init_list.begin(); it != init_list.end(); ++it)
        _data[idx++] = *it;
}

#29 楼

auto my_ints = {1,2,3};