将n个数按输入时顺序的逆序排列，用指针实现。并用指针实现字符串的逆序输出。

1. 将n个数按输入时顺序的逆序排列，用指针实现

#include <iostream>
using namespace std;

void reverse(int *arr, int n) {
    int *p1 = arr, *p2 = arr + n - 1;
    while (p1 < p2) {
        swap(*p1, *p2);
        p1++;
        p2--;
    }
}

int main() {
    int n;
    cout << "请输入 n：";
    cin >> n;

    int *arr = new int[n];
    cout << "请输入 " << n << " 个数：";
    for (int i = 0; i < n; i++) {
        cin >> *(arr + i);
    }

    reverse(arr, n);

    cout << "逆序输出：";
    for (int i = 0; i < n; i++) {
        cout << *(arr + i) << " ";
    }
    cout << endl;

    delete[] arr;
    return 0;
}

2. 用指针实现字符串的逆序输出

#include <iostream>
#include <cstring>
using namespace std;

void reverse(char *str) {
    int len = strlen(str);
    char *p1 = str, *p2 = str + len - 1;
    while (p1 < p2) {
        swap(*p1, *p2);
        p1++;
        p2--;
    }
}

int main() {
    char str[100];
    cout << "请输入字符串：";
    cin.getline(str, 100);

    reverse(str);

    cout << "逆序输出：" << str << endl;

    return 0;
}