cpp_learn/cpp_3_19_chapter6.cpp at master · coldran/cpp_learn · GitHub

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#include<iostream>
#include<initializer_list>
#include<string>
#include<vector>

using std::cout;
using std::cin;
using std::endl;
using std::string;
using std::vector;

voidexercise6_10(int *pA, int *pB)
{ // 指针交换两个int的值
int nTemp = *pA;
 *pA = *pB;
 *pB = nTemp;
}

voidexercise6_12(int &nA, int &nB)
{ // 引用交换两个int的值
int nTemp = nA;
 nA = nB;
 nB = nTemp;
}

voidexercise6_27(std::initializer_list<int> il)
{ // 使用 initializer_list计算列表的元素和
int nResult{0};
for(auto beg = il.begin(); beg != il.end(); ++beg)
 {
 nResult += *beg;
 }
 cout << nResult << endl;
}

voidtest1(std::initializer_list<string> sl)
{ // 查看elem的类型
for(constauto &elem : sl)
 cout << elem << endl;
}

intexercise6_33(vector<int>::iterator &itBegin, vector<int>::iterator &itEnd)
{ // 递归输出vector对象
if(itBegin != itEnd)
 {
 cout << *itBegin++ << endl;
exercise6_33(itBegin, itEnd);
 }
return0;
}

intexercise6_33(const vector<int> &vnTest)
{ // 递归输出vector对象
staticauto viBegin = vnTest.begin();
if(viBegin != vnTest.end())
 {
 cout << *viBegin++ << endl;
exercise6_33(vnTest);
 }
return0;
}

voidtest2()
{ // 测试，当vector赋值时，begin和end都变化，用第一个vector的迭代器根据第二个vector的值比对，会出现错误，实际上时迭代器会直接++到第二个迭代器的对应值
int k = 0;
 vector<int> i{1, 2, 3, 4};
 vector<int> j{i};
auto p = i.begin();
auto q = j.end();
while(p != q)
 {
 cout << k++ << "\t" << *p << endl;
 p++;
 }
}

string (&exercise6_36(void))[10]
{ // 返回数组的引用
static string sTest[10]{"a", "b"};
returnsTest;
}

using strarr = string[10];
strarr &exercise6_37_1(void)
{ // 类型别名
static string sTest[10]{"a", "b"};
returnsTest;
}

autoexercise6_37_2(void) -> string(&)[10]
{ // 后置返回类型
static string sTest[10]{"a", "b"};
returnsTest;
}

string nArr[10];
decltype(nArr) &exercise6_37_3(void)
{ // decltype关键字返回
static string sTest[10]{"a", "b"};
returnsTest;
}

intmain(int argc, charconst *argv[])
{
// int nA = 1, nB = 2;

// exercise6_10(&nA, &nB);
// cout << nA << "\t" << nB << endl;

// exercise6_12(nA, nB);
// cout << nA << "\t" << nB << endl;

// exercise6_27({1, 2, 3, 4, 5});

// test1({"a", "b", "cd", "efg"});

// vector<int> vnTest{1, 2, 3, 4, 5, 6, 7};
// auto Begin = vnTest.begin();
// auto End = vnTest.end();
// exercise6_33(Begin, End);
// exercise6_33(vnTest);

// test2();

// string (&sReturn)[10] = exercise6_36();
// for(auto i : sReturn)
// cout << i << endl;

// string (&sReturn)[10] = exercise6_37_1();

// string (&sReturn)[10] = exercise6_37_2();

// string (&sReturn)[10] = exercise6_37_3();

returnEXIT_SUCCESS;
}