Whats wrong in code, not working for all testcases

#include
#include

using namespace std;

void isPalaindrome(char s[]){

for(int i=0;i<strlen(s);i++){
if(s[i]%2!=0)
s[i]++;
else if(s[i]%2==0){
s[i]–;
}
}
cout<<s<<endl;

}
int main() {
//string s;
char s[1000];
cin.getline(s,1000);

isPalaindrome(s);
return 0;

}

hi @pushkarsingh5247_4b1a78f1d102c737 updated buddy