A Program To Copy One String To Another String Using a Pointer

Here we are going to discuss a copy of a string i.e. Copy One String To Another String Using a Pointer.

The copy means in programming is “=” sign.

Why?

Because assignment operator takes the responsibility to assign from right value (rvalue to lvalue).

Now we are going to cover some common points –

What is a string?

A string is a sequence of characters which is accompanied by a null keyword (\0) at the end. 

Syntax:

char s[10]="PROGRAM";

The above represents a string i.e., how a string is initialised.

For example:

This is how a string gets represented in a program, as said above it is terminated by a null by default.

What is a copy of a string?

When a content of one string gets copied to another string having the same or more dimension as the original string, is known as a copy of a string.

For example:

char s[10]="CODING";

char a[10];

Through the help of string keywords or techniques to copy a string, the content of string s gets copied to string a and holds the same value. This process is known as a copy of a string.

Now char a[10] holds:

How to copy one string to one another using a pointer?

The string gets copied through the following instruction:

Explanation:

Step-1: We take two string one string *str1 is declared as a pointer and the other str2 empty string.

Step-2: We take a separate function “copystring” where we pass the two strings which are initialised in pointer variables *a and *b in the function.

Step-3: A while loop is used which runs until the value of *a reaches ‘\0’ null, and the variable is incremented by one *a++ in each phase of the loop.

Step-4: In the body of the while loop as the loop goes on each character is extracted and is stored in another string variable *b as (*b++=*a++).

Step-5: In the end, as the loop gets terminated a null is added at the end of the second string *b, which is denoted as the end of the string.

Step-6: Hence the second string str2 is printed to get the result of the copy operation.

Implementation Part of Above Explanation:

#include<stdio.h>
void copystring(char *a, char *b);
int main()
{
	char *str1="CODING";
	char str2[10];
	copystring(str1,str2);
	printf("%s",str2);
	return 0;
}
void copystring(char *a, char *b)
{
	while(*a!='\0')
	{
		*b++=*a++;
	}
	b="\0";
}

Output:

CODING

We can also use the string functions to copy the contents of the string and there may be different logics too. We have used a logic which supports the copy of strings successfully.

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