The prototype of string manipulation function to realize __ function

Connect two char types: char * __cdecl strcat (char * DST, const char * src) {char * cp = DST; 
         while (*CP) cp++;

         while (*cp++ = *src++);
return (DST);
         }//C language standard library function strcpy, copying a string starting from the SRC address and containing the ' ' Terminator to the address space starting with dest: char * __cdecl strcpy (char * DST, const char * src) {
         char * cp = DST;          
	 while (*cp++ = *src++);
return (DST); }//Find first occurrence of character C in string s char * __cdecl STRCHR (const char * string, int ch) {while (*string && *string!)
         = (char) ch) string++;
         if (*string = = (char) ch) return ((char *) string);
return (NULL); /*c/c++ function, compares two strings, sets these two strings to be str1,str2, if STR1=STR2, returns 0, returns a negative number if str1<str2, and returns a positive number if str1>str2.

         * * int __cdecl strcmp (const char * src,const char * DST) {int ret = 0; while (!

         (ret = * (unsigned char *) src-* (unsigned char *) DST) && *dst) ++src, ++DST;
        if (Ret < 0)         ret =-1;

         else if (Ret > 0) ret = 1;
return (ret);
     }//Find string length size_t __cdecl strnlen (const char *STR, size_t maxsize) {size_t n;
     
     for (n = 0; n < maxsize && *str; n++, str++);
return n;
         }//To String length size_t __cdecl strlen (const char * str) {const char *eos = str;
         while (*eos++);
return (EOS-STR-1);
     }//Copy security Functions errno_t __cdecl strcpy_s (_char *_dest, size_t _size, const _char *_src) {_char *p;

     size_t available;
     _validate_string (_dest, _size);

     _validate_pointer_reset_string (_SRC, _dest, _size);
     p = _dest;
     Available = _size; while ((*p++ = *_src++)!= 0 &&--available > 0) {} if (available = 0) {_reset_string (_des
         T, _size);
     _return_buffer_too_small (_dest, _size);
     } _fill_string (_dest, _size, _size-available + 1);
_return_no_error; } char * __cdecl strncpy (char * dest, constchar * source, size_t count) {char *start = dest;
         while (count && (*dest++ = *source++))//copy str count--;

         if (count) while (--count) *dest++ = ';
 return (start); The/*STRSTR (STR1,STR2) function is used to determine whether a string str2 is a str1 substring. If it is, the function returns the address that str2 first appears in str1, otherwise, returns NULL.
         */char * __cdecl strstr (const char * str1, const char * str2) {char *CP = (char *) str1;
         Char *s1, *S2;

         if (!*STR2) return ((char *) str1);
                 while (*CP) {S1 = CP;

                 S2 = (char *) str2; while (*s1 && *s2 &&! (

                 *S1-*S2)) s1++, s2++;

                 if (!*S2) return (CP);
         cp++;
return (NULL);
The//STRSTR (STR1,STR2) function is used to determine whether a string str2 is a substring of str1. If so, the function returns the last occurrence of the str2 in str1 (that is, the first occurrence from right to left); otherwise, returns NULL. char * __cdecl STRRCHR (const char * string, int ch) {ChaR *start = (char *) string; while (*string++);
         /* Find end of String * */while (--string!= start && *string!= (char) ch);

         if (*string = = (char) ch) return ((char *) string);
return (NULL);

 }