catenate 2 strings

[nmakes]

I'm trying to make a function similar to strcat(char,char) in string.h header file. Somehow this code does not catenate the strings. Please help me make it better.

void strappend(char *a, char *b)
{
    int i;
      int start_pos = strlen(a);
    for (i=0; b[i]!='\0'; i++)
      {
        a[start_pos + i] = b[i];
      }
      a[i] = '\0';
}

Thanks in advance!

[Moschops]

How much space have you allocated for the string a? What happens if a can hold, say, four characters, and then you try to write an extra 10 characters from b after the end of it? Something bad happens. Don't forget to allow for such things.

Let's ignore that for a moment. Let's imagine that you have a string of size ten, a, and a string of size ten, b. Then your code starts concatenating. What is the value of i when the code finds the end of string b? 10. So where do you write the '\0'?

a[i] = '\0';
At a[10]. Is that the end of the new, concatentaed string? No, it is not.

[nmakes]

Yeah.. I solved it the next moment I posted this one. Actually in the last line I had to write a[start_pos + i] = '\0'; and not a[i] = '\0';
Anyway, thanks! :D