3.2
#include<iostream>
#include<string>
using namespace std;
int main()
{
//输入一行数据
string str;
cout << "please enter the string:";
getline(cin,str);
cout << "the string is:" << str << endl;
//输入单个字符
string str2,str3;
cout << "please enter the string:";
cin >> str2 >> str3;
cout << "the string is " << str2 << str3;
return 0;
}
3.4
#include<iostream>
#include<string>
using namespace std;
int main()
{
string s1,s2;
while(cin >> s1 >> s2)
{
if(s1 == s2)
cout <<"two strings equal"<< s1 << endl;
else
cout << "the larger string is " << (s1>s2?s1:s2) << endl;
}
return 0;
}
3.4.2
#include<iostream>
#include<string>
using namespace std;
int main()
{
string s1,s2;
while(cin >> s1 >> s2)
{
if(s1.size() == s2.size())
cout << "The two strings's length is same" << endl;
else
cout << "The larger string is :" << (s1.size()>s2.size()?s1:s2) << endl;
}
return 0;
}
#include<iostream>
#include<string>
using namespace std;
int main()
{
string largeStr;
string str;
while(cin >> str) //Ctrl + Z结束
{
largeStr += str;
}
cout << "The concatenated string is " << largeStr << endl;
return 0;
}
3.5.2
#include<iostream>
#include<string>
using namespace std;
int main()
{
string largeStr;
string str;
while(cin >> str)
{
if(largeStr.empty())
largeStr += str;
else
largeStr += " " + str;
}
cout << "The concatenated string is " << largeStr << endl;
return 0;
}
3.6
#include<iostream>
#include<string>
using namespace std;
int main()
{
string str;
cout << "please enter the String:";
cin >> str;
for(auto &s:str)
s = 'X';
cout << str << endl;
return 0;
}
3.8
#include<iostream>
#include<string>
using namespace std;
int main()
{
string str;
cout << "please enter the String:";
cin >> str;
decltype(str.size()) index = 0;
while(index<str.size())
{
str[index] = 'X';
index++;
}
cout << str << endl;
for(index = 0;index<str.size();index++)
str[index] = 'Y';
cout << str << endl;
return 0;
}
3.10
#include<iostream>
#include<string>
using namespace std;
int main()
{
string s;
cout << "Enter a string of characters including punctuation."<<endl;
while(cin >> s)
{
for(auto &i:s)
if(!ispunct(i))cout << i;
cout << endl;
}
return 0;
}
3.14
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> v1;
int i;
while(cin >> i)
{
v1.push_back(i);
}
for(int i = 0;i < v1.size();i++)
{
cout << v1[i] << endl;
}
return 0;
}
3.15
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main()
{
vector<string> vec;
string str;
while(cin >> str)
{
vec.push_back(str);
}
for(auto &v : vec)
{
cout << v << endl;
}
return 0;
}
3.16
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> v1;
cout << "{\n \"v1\":{\"size\":\"" << v1.size() << "\",\"value\":[";
for (auto i : v1) cout << i << ",";
if (!v1.empty()) cout << "\b";
cout << "]}" << endl;
vector<int> v2(10);
cout << " \"v2\":{\"size\":\"" << v2.size() << "\",\"value\":[";
for (auto i : v2) cout << i << ",";
if (!v2.empty()) cout << "\b";
cout << "]}" << endl;
vector<int> v3(10, 42);
cout << " \"v3\":{\"size\":\"" << v3.size() << "\",\"value\":[";
for (auto i : v3) cout << i << ",";
if (!v3.empty()) cout << "\b";
cout << "]}" << endl;
vector<int> v4{10};
cout << " \"v4\":{\"size\":\"" << v4.size() << "\",\"value\":[";
for (auto i : v4) cout << i << ",";
if (!v4.empty()) cout << "\b";
cout << "]}" << endl;
vector<int> v5{10, 42};
cout << " \"v5\":{\"size\":\"" << v5.size() << "\",\"value\":[";
for (auto i : v5) cout << i << ",";
if (!v5.empty()) cout << "\b";
cout << "]}" << endl;
vector<string> v6{10};
cout << " \"v6\":{\"size\":\"" << v6.size() << "\",\"value\":[";
for (auto i : v6)
if (i.empty())
cout << "(null)"
<< ",";
else
cout << i << ",";
if (!v6.empty()) cout << "\b";
cout << "]}" << endl;
vector<string> v7{10, "hi"};
cout << " \"v7\":{\"size\":\"" << v7.size() << "\",\"value\":[";
for (auto i : v7)
if (i.empty())
cout << "(null)"
<< ",";
else
cout << i << ",";
if (!v7.empty()) cout << "\b";
cout << "]}\n}" << endl;
return 0;
}
3.17
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main()
{
vector<string> vec;
string str;
while(cin >> str)
{
vec.push_back(str);
}
for(auto &s:vec) //s是一个字符串
{
for(auto &c:s) //c是单个字符char
{
c = toupper(c);//toupper函数只能对单个字符处理
}
}
for(auto s:vec)
{
cout << s << endl;
}
return 0;
}
3.19
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> v1(10,42);
vector<int> v2{42,42,42,42,42,42,42,42,42,42};
vector<int> v3;
for(int i = 0;i<10;i++)
{
v3.push_back(42);
}
cout << "The first approach is better!" << std::endl;
return 0;
}
3.20
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> vec;
int i;
while(cin >> i) vec.push_back(i);
if(vec.empty())
{
cout << "At least input one integer" << endl;
return -1;
}
else if(vec.size()==1)
{
cout << vec[0] << " don't have any adjacent elements.";
}
else
{
for(decltype(vec.size()) i = 0;i<vec.size()-1;i++)
{
cout << vec[i] + vec[i+1] << " ";
}
}
cout << endl;
decltype(vec.size()) size = vec.size();
if (size % 2 != 0)
size = size / 2 + 1;
else
size /= 2;
for(decltype(vec.size()) i = 0;i<size;i++)
{
cout << vec[i] + vec[vec.size()-1-i] << " ";
}
cout << endl;
return 0;
}
3.21
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> vec;
int i;
while(cin >> i) vec.push_back(i);
if(vec.empty())
{
cout << "At least input one integer" << endl;
return -1;
}
else if(vec.size()==1)
{
cout << vec[0] << " don't have any adjacent elements.";
}
else
{
for(decltype(vec.size()) i = 0;i<vec.size()-1;i++)
{
cout << vec[i] + vec[i+1] << " ";
}
}
cout << endl;
decltype(vec.size()) size = vec.size();
if (size % 2 != 0)
size = size / 2 + 1;
else
size /= 2;
for(decltype(vec.size()) i = 0;i<size;i++)
{
cout << vec[i] + vec[vec.size()-1-i] << " ";
}
cout << endl;
return 0;
}
3.22
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main()
{
vector<string> text;
string s;
while(getline(cin,s))
{
text.push_back(s);
}
for(auto it = text.begin();it < text.end()&&!it->empty();it++)
{
for(auto &c : *it) c = toupper(c);
cout << *it << endl;
}
return 0;
}
3.23
#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> v(10,1);
for(auto it = v.begin();it<v.end();it++)
{
*it = *it * 2;
}
for(auto i:v)
cout << i << endl;
return 0;
}
3.24
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main()
{
vector<int> ivec;
int i;
while(cin >> i)
{
ivec.push_back(i);
}
if (ivec.empty()) {
cout << "input at least one integer." << endl;
return -1;
}
else if (ivec.size() == 1) {
cout << *ivec.begin() << " has no adjacent elements.";
}
for(auto iter = ivec.begin();iter+1!=ivec.end();iter++)
{
cout << (*iter) + *(iter+1) << " ";
}
cout << endl;
for(auto b = ivec.begin(),e = (ivec.end()-1);b<=e;b++,e--)
{
cout << *b + *e << " ";
}
return 0;
}
3.25
#include <vector>
#include <iterator>
#include <iostream>
using std::vector;
using std::cout;
using std::cin;
using std::endl;
int main()
{
vector<unsigned> scores(11, 0);
unsigned grade;
while (cin >> grade)
if (grade <= 100) ++(*(scores.begin() + grade / 10));
for (auto score : scores) cout << score << " ";
cout << endl;
return 0;
}
3.31
#include<iostream>
#include<cstddef>
using namespace std;
int main()
{
int arr[10];
for(size_t i = 0;i<10;i++)
{
arr[i] = i;
}
for(auto &i:arr)
{
cout << i << " ";
}
return 0;
}
3.32
#include<iostream>
#include<vector>
using namespace std;
int main()
{
int arr[10];
for(size_t i = 0;i<10;i++)
{
arr[i] = i;
}
for(auto &i:arr)
{
cout << i << " ";
}
cout << endl;
int arr2[10];
for(size_t i = 0;i<10;i++)
{
arr2[i] = arr[i];
}
for(auto &i:arr2)
cout << i << " ";
cout << endl;
vector<int> vec(10);
for(auto iter = vec.begin();iter!=vec.end();iter++)
{
*iter = iter - vec.begin();
}
for(auto &i:vec) cout << i << " ";
cout << endl;
vector<int> v2(vec);
for(auto &i:v2) cout << i << " ";
cout << endl;
return 0;
}
3.35
#include<iostream>
#include<iterator>
using namespace std;
int main()
{
int arr[10];
int *b = begin(arr);
int *e = end(arr);
for(int *i = b; i!=e;i++)
*i = 0;
for(auto i:arr)
cout << i << " ";
return 0;
}
3.36
#include <iostream>
#include <vector>
#include <iterator>
using std::begin;
using std::end;
using std::cout;
using std::endl;
using std::vector;
// pb point to begin of the array, pe point to end of the array.
bool compare(int* const pb1, int* const pe1, int* const pb2, int* const pe2)
{
if ((pe1 - pb1) != (pe2 - pb2)) // have different size.
return false;
else {
for (int *i = pb1, *j = pb2; (i != pe1) && (j != pe2); ++i, ++j)
if (*i != *j) return false;
}
return true;
}
int main()
{
int arr1[3] = {0, 1, 2};
int arr2[3] = {0, 2, 4};
if (compare(begin(arr1), end(arr1), begin(arr2), end(arr2)))
cout << "The two arrays are equal." << endl;
else
cout << "The two arrays are not equal." << endl;
cout << "==========" << endl;
vector<int> vec1 = {0, 1, 2};
vector<int> vec2 = {0, 1, 2};
if (vec1 == vec2)
cout << "The two vectors are equal." << endl;
else
cout << "The two vectors are not equal." << endl;
return 0;
}
3.39
#include <iostream>
#include <string>
#include <cstring>
using std::cout;
using std::endl;
using std::string;
int main()
{
// use string.
string s1("Mooophy");
string s2("Pezy");
if (s1 == s2)
cout << "same string." << endl;
else if (s1 > s2)
cout << "Mooophy > Pezy" << endl;
else
cout << "Mooophy < Pezy" << endl;
cout << "=========" << endl;
// use C-Style character strings.
const char* cs1 = "Wangyue";
const char* cs2 = "Pezy";
auto result = strcmp(cs1, cs2);
if (result == 0)
cout << "same string." << endl;
else if (result < 0)
cout << "Wangyue < Pezy" << endl;
else
cout << "Wangyue > Pezy" << endl;
return 0;
}
3.40
#include<iostream>
#include<cstring>
using namespace std;
int main()
{
char cstr1[] = "Hello";
char cstr2[] = "World!";
size_t new_size = strlen(cstr1) + strlen(" ") + strlen(cstr2) + 1;
char *cstr3 = new char[new_size];
strcpy(cstr3,cstr1);
strcat(cstr3," ");
strcat(cstr3,cstr2);
cout << cstr3 << endl;
return 0;
}
3.41
#include<iostream>
#include<iterator>
#include<vector>
int main()
{
int arr[10] = {0,1,2,3,4,5,6,7,8,9};
std::vector<int> v(std::begin(arr),std::end(arr));
for(auto &i : v)
std::cout << i << " ";
return 0;
}
3.42
#include <iostream>
#include <vector>
using std::vector;
using std::cout;
using std::endl;
using std::begin;
using std::end;
int main()
{
vector<int> ivec{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
int int_arr[10];
for (int* i = begin(int_arr); i != end(int_arr); ++i)
*i = ivec[i - begin(int_arr)];
for (auto i : int_arr) cout << i << " ";
cout << endl;
return 0;
}
3.44
#include <iostream>
using std::cout;
using std::endl;
int main()
{
int ia[3][4] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
// a range for to manage the iteration
// use type alias
using int_array = int[4];
for (int_array& p : ia)
for (int q : p) cout << q << " ";
cout << endl;
// ordinary for loop using subscripts
for (size_t i = 0; i != 3; ++i)
for (size_t j = 0; j != 4; ++j) cout << ia[i][j] << " ";
cout << endl;
// using pointers.
// use type alias
for (int_array* p = ia; p != ia + 3; ++p)
for (int* q = *p; q != *p + 4; ++q) cout << *q << " ";
cout << endl;
return 0;
}
3.45
#include <iostream>
using std::cout;
using std::endl;
int main()
{
int ia[3][4] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
// a range for to manage the iteration
for (auto& p : ia)
for (int q : p) cout << q << " ";
cout << endl;
// ordinary for loop using subscripts
for (size_t i = 0; i != 3; ++i)
for (size_t j = 0; j != 4; ++j) cout << ia[i][j] << " ";
cout << endl;
// using pointers.
for (auto p = ia; p != ia + 3; ++p)
for (int* q = *p; q != *p + 4; ++q) cout << *q << " ";
cout << endl;
return 0;
}