C-Style String Operation

Here introduces C-style 'string' (mostly char[]) operation.

It's important that with classes and many more useful and Memory Safe functions, string shall not be processed with these functions.

1. strcpy(dst,source),return dstcopy source to destination, returning the address of destination. be cautious that it can cause memory leak. example:

   char b[5]={0};

   char a[]="abcdefghijklmn";

   cout << (int)strcpy(b,a);you'll get an address.

   cout << ' ';

   for(int i = 0;i<=15;i++)cout<<b[i];

   returns:

   1 2	6422204 abcdefghijklmn# #:memory leak^

2. strncpy(dst,src,n),return dstcopy n characters at most from source to destination. returning the address of destination. (better than strcpy to avoid memory leak.)

3. strcat(dst,src),return dstadd src to the end of dst. Returning the address of dst.

4. strncat(dst,src,n),return dst analogise with 2.

5. strlen(s),return intlength of a string(to the \0, not the size of a list).

6. strcmp(s1,s2),return intreturn (s1-s2).

7. strncmp(s1,s2,n),return int,anal. with 2.

8. strchr(s,ch),return addrreturn the address of the first ch in s.

   example:

   char a[]="abcdefghijklmn";

   cout<<strchr(a,'f'); returns: 6422278

   example:

   char a[]="abcdefghijklmn";

   cout<<(int)strchr(a,'q'); returns: 0

9. strrchr(s,ch),return addrreturn the address of the last ch in s.

10. strstr(s1,s2),return addranal with 7,but finding s2.