Exercises Section 3.2.2

Ex3.2

// 一次读取一行
#include<iostream>
#include<string>using namespace std;int main()
{string line;while (getline(cin, line)){cout << line << endl;}system("pause");return 0;
}// 一次读取一个 word
#include<iostream>
#include<string>using namespace std;int main()
{string word;while (cin >> word){cout << word << endl;}system("pause");return 0;
}

Ex3.3

在 string 输入操作中， whitespace characters 被忽略；在  getline 函数中，whitespace characters 正常输出。

Ex3.4

#include<iostream>
#include<string>using namespace std;int main()
{string s1;string s2;cout << "Please enter two string: " << endl;getline(cin, s1);getline(cin, s2);//比较 s1 和 s2 的大小if (s1 == s2)       // s1 和 s2 的长度和内容都相等{cout << "s1 and s2 are equal" << endl;}else if (s1 < s2){cout << "The larger string is s2" << endl;}else {cout << "The larger string is s1" << endl;}// 比较 s1 和 s2 长度的大小if (s1.size() == s2.size()){cout << "The length of s1 equals the length of s2" << endl;}else if (s1.size() < s2.size()){cout << "s2 is longer" << endl;}else {cout << "s1 is longer" << endl;}system("pause");return 0;
}

Ex3.5

// 拼接 string
#include<iostream>
#include<string>using namespace std;int main()
{string s;string result = "";while (getline(cin, s)){result += s;}cout << result << endl;system("pause");return 0;
}// 分别输出 string
#include<iostream>
#include<string>
#include<vector>using namespace std;int main()
{string s;vector<string> result;while (getline(cin, s)){result.push_back(s);}for (string i : result){cout << i << " ";}cout << endl;system("pause");return 0;
}

Exercises Section 3.2.3

Ex3.6

#include<iostream>
#include<string>using namespace std;int main()
{string s;getline(cin, s);for (auto &c : s){c = 'X';}cout << s << endl;system("pause");return 0;
}

Ex3.7

不能得到预期的结果，这是因为首先复制了 string 的一个副本，只是对其副本进行了修改。

Ex3.8

#include<iostream>
#include<string>using namespace std;int main()
{string s;getline(cin, s);auto it = s.begin();while (it != s.end()){(*it) = 'X';++it;}cout << s << endl;system("pause");return 0;
}

Ex3.9

    string s;cout << s[0] << endl;

输出 string s 的第一个字符；有效

Ex3.10

#include<iostream>
#include<string>using namespace std;int main()
{string s;getline(cin, s);for (auto &c : s){if (!ispunct(c)){cout << c;}}cout << endl;system("pause");return 0;
}

Ex3.11

    const string s = "Keep out!";for (auto &c : s){ /* ... */ }

合法；c 的类型为 const char&

Exercises Section 3.3.1

Ex3.12

a) vector<vector<int>> ivec; // 合法；ivec 是一个 vector，里面的元素是 存储 int 类型的 vector
b) vector<string> svec = ivec;   // 不合法； 利用一个 vector 给另外一个 vector 赋值，必须保证两个 vector 内的元素类型一样
c) vector<string> svec(10, "null");     // 合法；svec是一个 vector，有 10 个元素，每个元素为字符串值"null"

Ex3.13

a) vector<int> v1; // 没有元素
b) vector<int> v2(10);    // 10 个元素，每个元素值为 0
c) vector<int> v3(10, 42);    // 10 个元素，每个元素值为 42
d) vector<int> v4{10};        // 1 个元素，值为 10
e) vector<int> v5{10, 42};    // 2 个元素，值为 10 和 42
f) vector<string> v6{10}; // 10 个元素，每个元素值为 ""
g) vector<string> v7{10, "hi"}; // 10 个元素，每个元素值为 "hi"

Exercises Section 3.3.2

Ex3.14

#include<iostream>
#include<vector>
using namespace std;int main()
{int value;vector<int> result;while (cin >> value){result.push_back(value);}for (auto i : result){cout << i << " ";}cout << endl;system("pause");return 0;
}

Ex3.15

#include<iostream>
#include<vector>
#include<string>
using namespace std;int main()
{string value;vector<string> result;while (getline(cin, value)){result.push_back(value);}for (auto s : result){cout << s << " ";}cout << endl;system("pause");return 0;
}

Exercises Section 3.3.3

Ex3.17

#include<iostream>
#include<vector>
#include<string>using namespace std;int main()
{string word;vector<string> result;while (cin >> word){result.push_back(word);}for (auto & s : result){for (auto &c : s){c = toupper(c);}}for (auto i = 0; i != result.size(); ++i){if (i % 8 != 0)cout << result[i] << " ";else {cout << endl;cout << result[i] << " ";}}cout << endl;system("pause");return 0;
}

Ex3.18

vector<int> ivec;ivec[0] = 42;

不合法；修改如下：

vector<int> ivec;
ivec.push_back(42);

Ex3.19

vector<int> v1 = {42, 42, 42, 42, 42, 42, 42, 42, 42, 42};
vector<int> v2(10, 42);
vector<int> v3 = v2;

Ex3.20

#include<iostream>
#include<vector>using namespace std;int main()
{int value;vector<int> result;int sum = 0;while (cin >> value){result.push_back(value);}for (auto i = result.begin(), j = i + 1; i != result.end(); ++i){sum = (*i) + (*j);cout << sum << " ";}cout << endl;for (auto i = result.begin(), j = result.end() - 1; i <= j; ++i, --j){if (i != j){sum = (*i) + (*j);cout << sum << " ";}else {sum = (*i);cout << sum << " ";}}cout << endl;system("pause");return 0;
}

Exercises Section 3.4.1

Ex3.23

#include<iostream>
#include<vector>using namespace std;int main()
{int value;vector<int> result;for (int i = 0; i < 10; ++i){cin >> value;result.push_back(2 * value);}for (auto item = result.begin(); item != result.end(); ++item){cout << *item << " ";}cout << endl;system("pause");return 0;
}

Exercises Section 3.4.2

Ex3.26

mid = beg + (end - beg) / 2;   // 推荐
mid = (beg + end) / 2;        // 不推荐

原因：第二种可能造成整数溢出

Exercises Section 3.5.1

Ex3.27

unsigned buf_size = 1024;
a) int ia[buf_size];        // 非法；buf_size 不是一个常量
b) int ia[4 * 7 - 14];      // 合法
c) int ia[txt_size()];      // 如果 txt_size() 返回的是常量 int 类型则合法
d) char st[11] = "fundamental";      // 非法；最后的'\0'占一个字符，故而数组大小不够

Ex3.28

string sa[10];           // 元素值全为空字符串
int ia[10];             // 元素值全为0
int main()
{string sa2[10];        // 元素值全为空字符串int ia2[10];        // 元素值不确定，取决于编译器
}

Ex3.29

array 大小确定，而 vector 大小可以不确定。

Exercises Section 3.5.2

Ex3.30

    constexpr size_t array_size = 10;       int ia[array_size];for (size_t ix = 1; ix <= array_size; ++ix)       // 下标为0-9，没有 10 下标ia[ix] = ix;

Ex3.31

#include<iostream>using namespace std;int main()
{int a[10];for (int i = 0; i < 10; ++i){a[i] = i;}for (int i = 0; i < 10; ++i){cout << a[i] << " ";}cout << endl;system("pause");return 0;
}

Ex3.32

#include<iostream>
#include<vector>using namespace std;int main()
{int a[10], b[10];vector<int> s1;vector<int> s2;for (int i = 0; i < 10; ++i){a[i] = i;}for (int i = 0; i < 10; ++i){b[i] = a[i];}for (auto i = 0; i < 10; ++i){s1.push_back(i);}for (vector<int>::const_iterator it = s1.begin(); it != s1.end(); ++it){s2.push_back(*it);}for (vector<int>::const_iterator it = s2.begin(); it != s2.end(); ++it){cout << *it << " ";}cout << endl;system("pause");return 0;
}

Ex3.33

未初始化的数组的元素值取决于编译器

Exercises Section 3.5.3

Ex3.34

p1 += p2 - p1; // 将指针 p2 的值赋给指针 p1；如果 p1 被 const 修饰则非法

Ex3.35

#include<iostream>using namespace std;int main()
{int a[10];int *p = &a[10];for (int *it = a; it != p; ++it){*it = 0;}for (int x : a){cout << x << " ";}cout << endl;system("pause");return 0;
}

Ex3.36

// 比较数组是否相等
#include<iostream>using namespace std;int main()
{int arr1[10];int arr2[10];int size_arr1 = end(arr1) - begin(arr1);int size_arr2 = end(arr2) - begin(arr2);if (size_arr1 != size_arr2) {cout << "Differen. " << endl;return 0;}for (int i = 0; i != size_arr1; ++i) {if (arr1[i] != arr2[i]) {cout << "Different. " << endl;return 0;}}cout << "Same arr. " << endl;system("pause");return 0;
}// 比较vector 是否相等
#include<iostream>
#include<vector>using namespace std;int main()
{vector<int> ivec1{1, 2, 3};vector<int> ivec2{1, 2, 3};if (ivec1 == ivec2) {cout << "Same vector. " << endl;}else {cout << "Different. " << endl;}system("pause");return 0;
}

Exercises Section 3.5.4

Ex3.37

#include<iostream>using namespace std;int main()
{const char ca[] = {'h', 'e', 'l', 'l', 'o'};const char *cp = ca;while (*cp){cout << *cp << endl;++cp;}system("pause");return 0;
}

Ex3.38

C++ 中没有指针加法

Ex3.39

// C char[]
#include<iostream>
#include<cstring>using namespace std;int main()
{const char ca1[] = "string-A";const char ca2[] = "string-B";if (strcmp(ca1 , ca2) > 0) {cout << "string-A big" << endl;} else {cout << "string-B big" << endl;}system("pause");return 0;
}// C++ string
#include<iostream>
#include<string>using namespace std;int main()
{string s1 = "string-A";string s2 = "string-B";cout << "Big one is: ";if (s1 > s2) {cout << s1 << endl;} else {cout << s2 << endl;}system("pause");return 0;
}

Ex3.40

#include<cstring>
#include<iostream>using namespace std;int main()
{char s1[100] = "stringA";char s2[] = "stringB";strcat(s1 , s2);char s[100];strcpy(s , s1);cout << s << endl;system("pause");return 0;
}

Exercises Section 3.5.5

Ex3.41

#include<iostream>
#include<vector>using namespace std;int main()
{int value;vector<int> v1;int a[10];for (int i = 0; i < 10; ++i){cin >> value;a[i] = value;}for (int i = 0; i < 10; ++i){v1.push_back(a[i]);}for (auto i : v1){cout << i << " ";}cout << endl;system("pause");return 0;
}

Ex3.42

#include<iostream>
#include<vector>using namespace std;int main()
{int value;vector<int> v;while (cin >> value){v.push_back(value);}int a[v.size()];for (int i = 0; i < v.size(); ++i){a[i] = v[i];}for (int i = 0; i < v.size(); ++i){cout << a[i] << " ";}system("pause");return 0;
}

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Chapter 3: Strings、Vectors And Arrays

Exercises Section 3.2.2

Ex3.2

Ex3.3

Ex3.4

Ex3.5

Exercises Section 3.2.3

Ex3.6

Ex3.7

Ex3.8

Ex3.9

Ex3.10

Ex3.11

Exercises Section 3.3.1

Ex3.12

Ex3.13

Exercises Section 3.3.2

Ex3.14

Ex3.15

Exercises Section 3.3.3

Ex3.17

Ex3.18

Ex3.19

Ex3.20

Exercises Section 3.4.1

Ex3.23

Exercises Section 3.4.2

Ex3.26

Exercises Section 3.5.1

Ex3.27

Ex3.28

Ex3.29

Exercises Section 3.5.2

Ex3.30

Ex3.31

Ex3.32

Ex3.33

Exercises Section 3.5.3

Ex3.34

Ex3.35

Ex3.36

Exercises Section 3.5.4

Ex3.37

Ex3.38

Ex3.39

Ex3.40

Exercises Section 3.5.5

Ex3.41

Ex3.42

Chapter 3: Strings、Vectors And Arrays相关推荐

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