c＋＋把1234倒序输入，要求4321是整数（即四千三百二十)

#include
using namespace std;

int main(){
int n;//n是一个四位整数
int x;
int a, b, c, d;
cout << "输入一个四位整数:";
cin >> n;
a = n/1000;
b = (n - a * 1000)/100;
c = (n - a * 1000 - b * 100)/10;
d = n % 10;
x = d * 1000 + c * 100 + b * 10 + a;
cout << x;

return 0;

}

 #include <iostream>
using namespace std;
void revert(int n)
{
    if ( n>= 0 && n<= 9 )
    {
        cout<<n;
    }
    else
    {
        cout<<n % 10;
        revert(n/10);
    }   
}
int main()
{
    int n = 12345 ;
    revert(n);
}

将int型数据转换成string,对string反转完在转换回去就行了

void reverseStr(string& str)
{
    int n = str.length();

    for (int i = 0; i < n / 2; i++)
    {
        swap(str[i], str[n - i - 1]);
    }
}

int main()
{
    string num;
    cin >> num;
    reverseStr(num);
    int result = std::stoi(num);
    cout << result;
    
    return 0;
}

#include <stdio.h>

int res(int r)
{
int s = 0;

while(r != 0)
{
    s *= 10;
    s += r % 10;
    r /= 10; 
}

return s;

}
int main()
{
// printf("hello world!!");

int a = 1234;

//scanf("%d", &a);
printf("%d", res(a));
getchar();
getchar();
}