练习6.21
int compare(const int i1,const int* i2) {
return i1 > *i2 ? i1 : *i2;
}
int main() {
int a = 10;
int b = 20;
cout << compare(a, &b); //20
}
练习6.22
void change_pointer(int *&i1, int *&i2) {
int* temp = i1; //temp暂时保存i1的值
i1 = i2; //i1现在拷贝i2的值
i2 = temp; //i2现在拷贝i1的值
}
int main() {
int a = 30;
int b = 50;
int* c = &a;
int* d = &b;
cout << a << endl;
cout << b << endl;
cout << c << endl;
cout << d << endl;
cout << *c << endl;
cout << *d << endl;
change_pointer(c, d);
cout << a << endl; //不变
cout << b << endl; //不变
cout << c << endl; //交换,形参是引用的指针
cout << d << endl; //交换,形参是引用的指针
cout << *c << endl;//交换,c现在保存变量b的地址
cout << *d << endl;//交换,d现在保存变量d的地址
}
练习6.23
void print1(const int* beg, const int* end)
{
while (beg != end)
cout << *beg++ << endl;
}
void print2(const int* p)
{
cout << *p << endl;
}
void print3(const int ia[], size_t size)
{
for (size_t i = 0; i != size; ++i)
cout << ia[i] << endl;
}
int main() {
int i = 0, j[2] = { 0,1 };
//print1(i),不合法
print1(begin(j), end(j)); //0 1
print2(&i); //p指向i。//0
print2(j); //j是数组,初始值是指向数组的第一个元素的指针 //0
print3(j,end(j)-begin(j)); //0 1
}
练习6.24
当k数组的元素是10个时,原程序正确:
void print(const int ia[10])
{
for (size_t i = 0;i != 10;++i)
cout << ia[i] << endl; //输出数组中的每一个元素
}
int main() {
const int k[] = { 0,1,2,3,4,5,6,7,8,9 };
print(k);
}
但是当k不是10个元素时,如果少于10个元素,最后多输出值,如果多于10个元素,则10以后的元素不输出,最好是根据k的元素数量,来输出:
void print3(const int ia[], size_t size)
{
for (size_t i = 0; i != size; ++i)
cout << ia[i] << endl;
}
如有错误,请多指教!