c++ - Create my own strlen and substring functions -

i trying create own strlen , substr functions , have 1 problem.
example, let have string abc, strlen return 3, let want cut string 0 1 should return me a,but trash values, if insert substr new char , check length recieve 14.
code:

int len(char *w){     int count=0;     int i=0;     while (w[i]!='\0')     {         count++;         i++;     }     //cout<<"length of word is:"<<count<<"\n";     return count;  }  char *subs(char *w,int s,int e){     int i,j;     int size=0;size=(e-s);     //cout<<"new size is:"<<size<<"\n";     char *neww=new char[size];      for(i=0,j=s;j<e;i++,j++)     {         neww[i]=w[j];       }      return neww;  }  int main(){     char* x="abc";     //int v=len(x);     //cout<<v;     char *n=subs(x,0,1);     cout << len(n);     for(int g=0;g<len(n);g++)     //cout<<n[g];      return 0; } 

i comments did wrong, thanks!

change condition loop for(i = 0, j = s ; j < e && w[j] != '\0'; i++, j++) , need allocate size +1 since have add \0 @ end of string.