This code is not working for negative ascii values?what should i do to make it work

[jatin_wadhwa]

#include
#include
#include
#include<stdio.h>
#include
using namespace std;

int main()
{

char s[10000],t[100000];
int i=0,l=0;
char ch;
cin>>ch;
while(ch!=’\n’)
{
s[i]=ch;
i++;
ch=cin.get();
}
int m= strlen(s);

for(i=0; i<m-1; i++)
{
t[l]=s[i];
l++;
int z= s[i+1]-s[i];
t[l]=z+‘0’;

l++;

}
t[l]=s[m-1];
l++;
for(i=0; i<l; i++)
{
cout<<t[i];
}
return 0;
}

[Ishitagambhir]

@jatin_wadhwa please save your code on ide.codingblocks.com and share the link here.