This is the simple implementation of the “Copy” function using the pointers. This program copies the content of one string to another.

Logic : The program asks the user to input the string to copy and stores using the pointer str1. The inner function “stcpy” takes 2 string pointers as arguments. By keeping the length as the reference, it traces till EOF , for each i of this iteration it copies the i-th  letter to the destination string, i.e str2. After the EOL, it puts a NULL to the second line. That gives the duplicated string of the entered.

This function copies the string using the pointer, where earlier program copies the string directly.

#include<stdio.h>
#include<conio.h>
void stcpy(char *str1, char *str2);
void main()
{
char *str1, *str2;
clrscr();
printf(“\n\n\t ENTER A STRING…: “);
gets(str1);
stcpy(str1,str2);
printf(“\n\t THE COPIED STRING IS…: “);
puts(str2);
getch();
}
void stcpy(char *str1, char *str2)
{
int i, len = 0;
while(*(str1+len)!=’\0′)
len++;
for(i=0;i<len;i++)
*(str2+i) = *(str1+i);
*(str2+i) = ‘\0′;
}
Download exe and source code here.