I am getting WA for the following code of The Next Palindrome ... it is giving garbage values for long strings (like 200 or more characters).
bt it is giving AC if I output string p,character wise using a loop... Plz help me why it is giving garbage values. 
#include<iostream>
#include<string>
using namespace std;
void palindrome();
int main()
{
int t=0;// test cases
cin>>t;
for(int i=0;i<t;i++)
{
palindrome();
}
return 0;
}
void palindrome()
{
string n;// number
cin>>n;
int d=n.length();// no of digits
string inlf=n.substr(0,(d+1)/2);
string filf=n.substr(d/2,(d+1)/2);
char copy[d/2+3];
string comp=inlf;
int k=comp.length();
for(int i=0;i<k/2;i++)
{
char temp=comp[i];
comp[i]=comp[k-1-i];
comp[k-1-i]=temp;
}
for(int i=0;i<d/2;i++)
{
copy[d/2-1-i]=inlf[i];
}
string p=inlf+copy;//palindrome
if(d==1) p=inlf;
if(d==2) p=inlf+inlf;
if(d==3) { p=n; p[2]=n[0];}
if(filf>=comp)
{
int ch=n[((d-1)/2)]-48;
int i=0;
while(ch==9)
{
p[((d-1)/2)-i]='0';
p[((d)/2)+i]='0';
++i;
ch=n[((d-1)/2)-i]-48;
if(i==(d+1)/2)
{
break;
}
}
if(i==(d+1)/2&&n[0]=='9'&&n[1]=='9')
{
p[0]='1';
for(int i=1;i<d;i++)
{
p[i]='0';
}
p=p+"1";
}
else
{
++ch;
char change=ch+'0';
p[d/2+i]=change;
p[(d-1)/2-i]=change;
if (n=="9") p="11";
}
}
cout<<p<<endl;
}
Thnx
