vc++数组与指针混合应用问题

Question

1.使用下标法将一个字符串拼接到另一个字符串后面，比如“abcfe”后面拼接“12345”
2.使用下标法将字符串逆序排列后输出，比如“abcd123”排列为“321dcba”后输出
3.使用指针变量将一个字符串拼接到另一个字符串的后面，比如“abcfe”后面拼接“12345”，称为“abcfe12345”
4.使用指针变量实现字符串的逆序排列后输出，比如将字符串“abcd123”逆序排列为“321dcba”

Answer 1

1.下标法拼接

#include <iostream>
using namespace std;
#define MAXLEN 100
int main()
{
    char src1[MAXLEN], src2[MAXLEN];
    cin >> src1 >> src2; //读取两个字符串
    //下标法拼接
    int i = 0, j = 0;
    //将下标移动到src1最后
    while (src1[i] != '\0')
        i++;
    //将src2拼接到src1
    while (src2[j] != '\0')
    {
        src1[i] = src2[j];
        i++;
        j++;
    }
    src1[i] = '\0'; //结尾
    cout << src1 << endl;
    return 0;
}

1. 下标法逆序

#include <iostream>
#include <cstring>
using namespace std;
#define MAXLEN 100
int main()
{
    char src1[MAXLEN], tmp;
    cin >> src1; //读取两个字符串
    //下标法
    int i = 0, j = strlen(src1)-1;
    
    //逆序
    while (i < j)
    {
        tmp = src1[i];
        src1[i] = src1[j];
        src1[j] = tmp;
        i++;
        j--;
    }
    
    cout << src1 << endl;
    return 0;
}

3.指针法拼接

#include <iostream>
using namespace std;
#define MAXLEN 100
int main()
{
    char src1[MAXLEN], src2[MAXLEN];
    char* p1, * p2;
    p1 = src1;
    p2 = src2;
    cin >> src1 >> src2; //读取两个字符串
    //指针法拼接
   
   
    while (*p1 != '\0')
        p1++;
    //将src2拼接到src1
    while (*p2 != '\0')
    {
        *p1 = *p2;
        p1++;
        p2++;
    }
    *p1 = '\0'; //结尾
    p1 = src1; //重回数组头
    cout << p1 << endl;
    return 0;
}

4.指针法逆序

#include <iostream>
#include <cstring>
using namespace std;
#define MAXLEN 100
int main()
{
    char src1[MAXLEN], tmp;
    char* p = src1;
    char* pend;
    cin >> src1; //读取字符串
    
    pend = p + strlen(src1);
    pend--;
    //逆序
    while (p < pend)
    {
        tmp = *p;
        *p = *pend;
        *pend = tmp;
        p++;
        pend--;
    }

    p = src1;//重回数组头
    cout << p << endl;
    return 0;
}