Why garbage value showing up?

Question

User enters a string like '3+2+1' or '1+3+2+1+3+1'. And I just have to sort the string. But after 4-5 test cases error shows up.

Input  - 2
Output - �

Input  - 2+1+2+2+2+3+1+3+1+2
Output - �+1+1+1+2+2+2+2+2+3

#include<iostream>
using namespace std;

int main()
{

    string s;
    cin>>s;

    for(int i=0;i<s.size();i+=2)
    {
        for(int j=0;j<(s.size()-i);j+=2)
        {
            if(s[j]>s[j+2])
            {
                swap(s[j],s[j+2]);
            }
        }
    }

    cout<<s;
    return 0;
}

Answer 1

As ggorlen said, garbage is showing up because you're accessing a value that's out of bounds. Try checking if your "j" index plus 2 is out of bounds before doing any swap.

#include<iostream>
using namespace std;

int main()
{

    string s;
    cin>>s;

    for(int i=0;i<s.size();i+=2)
    {
        for(int j=0;j<(s.size()-i);j+=2)
        {
            if(j+2 < s.size() && s[j]>s[j+2])
            {
                swap(s[j],s[j+2]);
            }
        }
    }

    cout<<s;
    return 0;
}

Input 2+1+2+2+2+3+1+3+1+2

Output 1+1+1+2+2+2+2+2+3+3