Find suffix, prefix, and substring of strings using c++ language

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

bool isSuffix(string s1, string s2)
{
    int n1 = s1.length(), n2 = s2.length();
    if (n1 > n2)
        return false;
    for (int i=0; i<n1; i++)
        if (s1[n1 - i - 1] != s2[n2 - i - 1])
            return false;
    return true;
}

bool isPrefix(string s1, string s2)
{
    int n1 = s1.length(), n2 = s2.length();
    if (n1 > n2)
        return false;
    for (int i=0; i<n1; i++)
        if (s1[i] != s2[i])
            return false;
    return true;
}

bool Substring(string s1, string s2)
{
    int n1 = s1.length(), n2 = s2.length();
    if (n1 > n2)
        return false;
    for (int i=0; i<s2[i]!='\0'; i++)
        if (s1[i]!=s2[i])
            return false;
    return true;
}


int main()
{
    //getline(cin,s1); //getline(cin,s2);
    string s1 = "saat", s2 = "aaabsaat";

    bool result1 = isSuffix(s1, s2);
    bool result2 = isPrefix(s1, s2);
    bool result3 = Substring(s1, s2);
    if(result1 || result2 || result3)
    {
        if (result1)
            cout << "Suffix"<<endl;
        if (result2)
            cout << "Prefix"<<endl;
        if (result3)
            cout << "Sub-String"<<endl;
    }
    else
    {
        cout<<"Not suffix, prefix or sub-string"<<endl;
    }
    return 0;
}
<-------------------------->===<-------------------------->
sample input:
saat
aaabsaat

sample output:
Suffix