Задание со строками (найти ошибку)

#include <iostream>
#include <string.h>
using namespace std;
int main()  
{
int i,j;
char s[100];
char s1[100];
char s2[100];
char res[100];
cout<<"Vvedite stroky: "<<endl;
cin>>s;
int len=strlen(s);
for (i=1;i<len-1;i++)
{
strcpy(res,"");
if (s[i]=='.') 
{
strcpy(s1,"");
for (j=i-1;j>=0;j--)
{
if (s[j]=='0'||s[j]=='1'||s[j]=='2'||s[j]=='3'||s[j]=='4'||s[j]=='5'||s[j]=='6'||s[j]=='7'||s[j]=='8'||s[j]=='9') 
{
char tmp[100];
strcpy(tmp,s1);
strcpy(s1,"");
s1[0]=s[j];
strcat(s1,tmp);
}
else
{
break;
}
}
strcpy(s2,"\0");
for (j=i+1;j<len;j++)
{
if (s[j]=='0'||s[j]=='1'||s[j]=='2'||s[j]=='3'||s[j]=='4'||s[j]=='5'||s[j]=='6'||s[j]=='7'||s[j]=='8'||s[j]=='9')
{
s2[j-i-1]=s[j];
s2[j-i]='\0';
}
else
{
break;
}
}
if (strlen(s1)>0&&strlen(s2)>0)
{
bool plus=false;
int t=i-strlen(s1)-1;
if (t>=0)
 {
if (s[t]=='+'||s[t]=='-') 
{
res[0]=s[t];
 res[1]='\0';
plus=true;
 }
}
strcat(res,s1);
if (plus)
{
res[strlen(s1)+1]=s[i];
res[strlen(s1)+2]='\0';
}
else
{
res[strlen(s1)]=s[i];
res[strlen(s1)+1]='\0';
}
strcat(res,s2);
break;
}
}
}
if (strlen(res)>0)
{
cout<<res<<endl;
}
else
{
cout<<"Ne naideno!"<<endl;
}
system ("pause");
return 0;
}