C++primer[习题][第三章][11-20]

• 3.11

如果不改变c的值合法，改变c的值就不合法。
c的类型为const char &。

• 3.12

vector

vector<int> ivec;
int tmp;
while (cin >> tmp)
{
    ivec.push_back(tmp);
}

• 3.15

vector<string> svec;
string s;
while (cin >> s)
{
    svec.push_back(s);
}

• 3.16

v1:
size:0

v2:0 0 0 0 0 0 0 0 0 0
size:10

v3:42 42 42 42 42 42 42 42 42 42
size:10

v4:10
size:1

v5:10 42
size:2

v6:
size:10

v7:hi hi hi hi hi hi hi hi hi hi
size:10

• 3.17

vector<string> svec;
string str;
while (cin >> str)
{
    svec.push_back(str);
}
for (auto &s : svec)
{
    for (auto &c : s)
    {
        c = toupper(c);
    }
    cout << s << endl;
}

• 3.18

不合法。

vector ivec;
ivec.push_back(42);

• 3.19

vector<int> ivec1(10, 42);

vector<int> ivec2{ 42, 42, 42,42,42,42,42,42,42,42 };

vector<int> ivec3;
for (int i = 0; i < 10; i++)
    ivec3.push_back(42);

相同元素第一种比较好。

• 3.20

vector<int> ivec(10, 42);
for (auto i = 0; i < ivec.size() - 1; i++)
    cout << ivec[i] + ivec[i + 1] << " ";

vector<int> ivec(10, 42);
for (auto i = 0; i < ivec.size(); i++)
    cout << ivec[i] + ivec[ivec.size() - 1 - i] << " ";