为什么在连接 2 个字符串时出现错误？

Question

I know that dest is a pointer and it holds the address of dest[0], ie *dest would give me dest[0] so I basically wanted to change the value of (dest+l)(which is currently having address of '\0') to the address of src[0], but I am getting weird outputs.

dest=final works then why does this code snippet fail?

char* strcat(char* dest, char*src){
    char* final;
    int l=strlen(dest);
    final=dest;
    int b=0,i;
    char* ans;
    final+=l;
    final=src;
    final-=l;
    dest=final;
    printf("%s",final);
    return dest;

}

EDIT: after reading the comments I made some changes to my code but now it gives me RE

char* strct(char* dest, char*src){
    char** final;
    int l=strlen(dest);
    *final=dest;
    int b=0,i;
    char* ans;
    final+=l;
    *final=src;
    final-=l;
    printf("%s",*final);
    return *final;
}

Answer 1

The pointer to pointer version added nothing but extra stars and extra bugs, so lets ignore that one...

Now, what does the original code do:

• final=dest; Now final points at dest .
• final+=l; Now final points at the null terminator in dest .
• final=src; Now final points at src and it forgets all about pointing at dest . This doesn't make sense.
• Instead of final=src you should have done strcpy(final, src); . This assuming that dest is large enough to contain the src string to begin with.

A simpler implementation would be:

char* strcat (char* dest, const char* src)
{
  strcpy(dest+strlen(dest), src);
  return dest;
}

This is essentially the very same thing as you attempted, just less verbose.