#include <stdio.h>
 
void substrcpy1(char *target, const char *src, int start, int length);
void substrcpy2(char *target, const char *src, int start, int length);
void substrcpy3(char *target, const char *src, int start, int length);
void substrcpy4(char *target, const char *src, int start, int length);
 
int main(void)
{
   char a[100] = "C/C++ sample code archive.";
   char b[100];
   substrcpy4(b, a, 0, 5);
   printf("\n%s", b);
   return 0;
}
/*************************************************************************/
void substrcpy1(char *target, const char *src, int start, int length)
{
   int i, j;
 
   for (j = 0, i = start; i < start + length && src[i] != '\0'; i++, j++)
      target[j] = src[i];
   target[j] = '\0';
}
/*************************************************************************/
void substrcpy2(char *target, const char *src, int start, int length)
{
   const char *p = src + start; 
   const char *q = src + start + length; 
 
   for (; p < q && *p != '\0'; p++, target++) 
      *target = *p; 
   *target = '\0'; 
} 
/*************************************************************************/ 
void substrcpy3(char *target, const char *src, int start, int length) 
 
{ 
   int i, j;
 
   for (j = i = 0; src[i] != '\0'; i++) { 
      if (i < start) 
         continue; 
      if (j >= length) 
         break; 
      target[j] = src[i]; 
      j++; 
   } 
   target[j] = '\0'; 
} 
/*************************************************************************/ 
void substrcpy4(char *target, const char *src, int start, int length) 
{ 
   int i; 
 
   for (i = 0; src[i] != '\0' && i < length; i++) 
      target[i] = src[i + start]; 
   target[i] = '\0'; 
}