[数据结构与算法]C++STL算法generate/generate_n（21）

generate

template<class _FwdIt,class _Fn> inline
void generate(_FwdIt _First, _FwdIt _Last, _Fn _Func)

将函数对象生成的元素赋值给容器。

参数

first 和 last 都为正向迭代器，[first, last) 用于赋值的范围；

func自定义规则，lambda函数或者函数，或者函数对象。

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <string>
#include<iterator>

int main()
{	
	//函数
	std::vector<int> b(5);//没确定配容器大小，不分配内存
	std::generate(std::begin(b), std::end(b), value);
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	//仿函数
	std::generate(std::begin(b), std::end(b), fill());
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	//lambda
	std::generate(std::begin(b), std::end(b), [&]() {
		static int a = 10;
		return a++;
	});
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	return -1;
}

//输出
b fill vector: 0, 1, 2, 3, 4,
b fill vector: 6, 7, 8, 9, 10,
b fill vector: 10, 11, 12, 13, 14,

?generate_n

函数原型

template<class _OutIt, class _Diff, class _Fn> inline
_OutIt generate_n(_OutIt _Dest, const _Diff _Count_raw, _Fn _Func)

将函数对象生成的元素赋值给容器n个元素。

参数

_Dest 填充容器

_Diff _Count_raw 数目

_Func?自定义规则，lambda函数或者函数，或者函数对象

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <string>
#include<iterator>

int main()
{	
	//函数
	std::vector<int> b(5);//没确定配容器大小，不分配内存
	std::generate_n(std::begin(b), b.size(), value);
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	//仿函数
	std::generate_n(std::begin(b), b.size(), fill());
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	//lambda
	std::generate_n(std::begin(b), b.size(), [&]() {
		static int a = 10;
		return a++;
	});
	std::cout << "b fill vector: ";
	std::for_each(std::begin(b), std::end(b), [](int value) {
		std::cout << value << ", ";
	});
	std::cout << std::endl;

	return -1;
}

//输出
b fill vector: 0, 1, 2, 3, 4,
b fill vector: 6, 7, 8, 9, 10,
b fill vector: 10, 11, 12, 13, 14,