Program:

#include<stdio.h>
int main() {
char s1[100], s2[100];
int i;
printf("\nEnter the string :");
gets(s1);
i = 0;
while (s1[i] != '\0') {
s2[i] = s1[i];
i++;
}

s2[i] = '\0';
printf("\nCopied String is %s ", s2);
return (0);
}

Output:

Enter the string: KT280

Copied String: KT280

User Defined Function:
i = 0;
while (s1[i] != '\0') {
s2[i] = s1[i];
i++;
}

Explanation:

• Scan Entered String From Left to Right, Character by Character.
• In Each Iteration Copy One Character To New String Variable.
• As soon as Source or Original String Ends, Process of Coping Character Stops but we still haven’t Copied NULL Character into new String so, Append Null Character to New String.