4.7编写代码实现一个数组赋值给另外一个数组,然后将这段代码改用vector实现。考虑如何将一个vector 赋值给另一个vector。
int main()
{
int a[3] = { 1,2,3 };
int b[3];
cout << "array :" << endl;
for (int i = 0; i < 3; i++)
{
b[i] = a[i];
cout << b[i] << endl;
}
vector
ivec1 = { 1, 2, 3 };
cout << "ivec1:" << endl;
for (vector
::iterator iter = ivec1.begin(); iter != ivec1.end(); ++iter) { cout <<*iter<< endl; } vector
ivec2(ivec1); vector
vec; vec = ivec2; cout << "ivec2:" << endl; for (vector
::iterator iter = ivec2.begin(); iter != ivec2.end(); ++iter) { cout << *iter << endl; } cout << "vec:" << endl; for (vector
::iterator iter = vec.begin(); iter != vec.end(); ++iter) { cout << *iter << endl; } return 0; }
4.8 编写程序判断两个数组是否相等,然后编写一段类似的程序比较两个vector。
int main()
{
int a[3] = { 1, 2, 3 };
int b[3] = { 1, 2, 3 };
cout << "use array:" << endl;
if (sizeof(a) / sizeof(int) == sizeof(b) / sizeof(int))
{
size_t i = 0;
for (i; i < sizeof(a) / sizeof(int); ++i)
{
if (a[i] != b[i])
{
cout << "两数组不相等" << endl;
break;
}
}
if (sizeof(a) / sizeof(int) == i)
{
cout << "两数组相等" << endl;
}
}
cout << "use vector :" << endl;
vector
vec = { 1, 2, 3, 4 };
vector
vec2 = { 1, 2, 3, 4 }; if (vec == vec2){ cout << "两数组相等" << endl; } else cout << "两数组不相等" << endl; return 0; }
4.9 编写程序定义一个有10个int型元素的数组,并以其在数组中的位置作为各元素的初值。
int main()
{
int a[10];
for (int i = 0; i < 10; ++i){
a[i] = i;
cout << a[i] << endl;
}
cout << "use vector" << endl;
vector
vec;
for (int i = 0; i < 10; ++i){
vec.push_back(i);
}
for (vector
::iterator iter = vec.begin(); iter != vec.end(); ++iter){ cout << *iter << endl; } return 0; }
4.14 编写代码修改指针的值,然后在编写代码修改指针所指对象的值。
int main()
{
int a (1),c(2);
int *b = &a;
b = &c;
*b = 6;
return 0;
}
4.16 下列程序实现什么功能?
int main()
{
int i = 42, j = 1024;
int *p1 = &i, *p2 = &j;
*p2 = *p1 * *p2;
*p1 *= *p1;
cout << *p1 << " "<<*p2 << endl;
return 0;
}
4.18 编写一个程序,使用指针把一个int型数组的所有元素设置成0。
int main()
{
int a[3] = { 1, 2, 3 };
for (int *p = a; p != a + 3; ++p){
*p = 0;
}
for (int i = 0; i < 3; ++i){
cout << a[i] << endl;
}
}
4.25 编写程序比较两个string字符串,然后编写程序比较两个C风格字符串。
int main()
{
cout << "C++ style!" << endl;
string str1 = "hello world";
string str2 = "good well";
if (str1 == str2){
cout << "两字符串相等" << endl;
}
else
cout << "两字符串不相等" << endl;
cout << "C style!" << endl;
char ch1[] = "hello world";
char ch2[] = "good well";
if (!strcmp(ch1, ch2)){
cout << "两字符串相等" << endl;
}
else
cout << "两字符串不相等" << endl;
}