C program to swap two strings

For swapping two strings from one location to another location, we use strcpy() function.

An array of characters (or) collection of characters is called a string.

Declaration

Following is the declaration for an array −

char stringname [size];

For example, char string[50]; string of length 50 characters.

Initialization

• Using single character constant

char string[10] = { ‘H’, ‘e’, ‘l’, ‘l’, ‘o’ ,‘\0’}

• Using string constants

char string[10] = "Hello":;

Accessing

There is a control string "%s" used for accessing the string till it encounters ‘\0’

strcpy ( )

This function is used for copying source string into destination string.

The length of the destination string is greater than or equal to the source string.

The syntax for strcpy() function is as follows −

strcpy (Destination string, Source String);

For example,

char a[50];            char a[50];
strcpy ("Hello",a);    strcpy ( a,"hello");
output: error          output: a= "Hello"

Program

Following is the C program to swap two strings by using strcpy() function −

#include<stdio.h>
#include<string.h>
main(){
   char s1[10],s2[10],s3[10];
   printf("Enter String 1\n");
   gets(s1);
   printf("Enter String 2\n");
   gets(s2);
   printf("Before Swapping\n");
   printf("String 1 : %s\n",s1);
   printf("String 2 : %s\n",s2);
   strcpy(s3,s1);
   strcpy(s1,s2);
   strcpy(s2,s3);
   printf("After Swapping:\n");
   printf("String 1 : %s\n",s1);
   printf("String 2 : %s\n",s2);
}

Output

When the above program is executed, it produces the following result −

Enter String 1
Tutorial
Enter String 2
Point
Before Swapping
String 1: Tutorial
String 2: Point
After Swapping:
String 1: Point
String 2: Tutorial