C Program to swap two numbers without using third variable

• C program to swap two numbers without using third variable.
• Yes we can swap two variables without using third variable.
• We have four different ways to swap two numbers without using third variable.
• Lets see an example C program on how to swap two numbers without using third variable and without using function.

Program #1: Write a simple C program to swap two numbers without using third variable

1. #include <stdio.h>
2. #include <stdlib.h>
3.  
4. int main(int argc, char *argv[])
5. {
6.   int a,b;
7.   printf("Please enter two integer numbers to swap\n");
8.   scanf("%d%d",&a,&b);
9.   printf("before swapping\n");
10.   printf("a=%d\n",a); 
11.   printf("b=%d",b);   
12.   
13.     a=b+a;
14.     b=a-b;
15.     a=a-b;
16.     
17.   printf("\nafter swapping\n");
18.   printf("a=%d\n",a); 
19.   printf("b=%d",b); 
20.   getch();
21.   
22. }

Output:

Program #2: Write a simple C program to swap two numbers without using third variable

1. #include <stdio.h>
2. #include <stdlib.h>
3.  
4. int main(int argc, char *argv[])
5. {
6.   int a,b;
7.   printf("Please enter two integer numbers to swap\n");
8.   scanf("%d%d",&a,&b);
9.   printf("before swapping\n");
10.   printf("a=%d\n",a); 
11.   printf("b=%d",b);   
12.  
13.   a=a+b-(b=a); 
14.     
15.   printf("\nafter swapping\n");
16.   printf("a=%d\n",a); 
17.   printf("b=%d",b); 
18.   getch();
19.   
20. }

Output:

1. Please enter two integers numbers to swap
2. 30
3. 40
4. before swapping
5. a=30
6. b=40
7. after swapping
8. a=40
9. b=30

Program #3: Write a simple C program to swap two numbers without using third variable : call by value

1. #include <stdio.h>
2. #include <stdlib.h>
3. int main(int argc, char *argv[])
4. {
5.   
6.   int a=12, b=13;
7.     a=a^b;
8.     b=a^b;
9.     a=b^a;
10.    printf("a=%d\n",a); 
11.  printf("b=%d",b); 
12.   getch();
13.   
14. }

  Output:

1. a=13
2. b=12

Program #4: Write a simple C program to swap two numbers without using third variable : call by value

1. #include <stdio.h>
2. #include <stdlib.h>
3. int main(int argc, char *argv[])
4. {
5.   
6.   int a=12, b=13;
7.      a=b-~a-1;
8.     b=a+~b+1;
9.      a=a+~b+1;
10.    printf("a=%d\n",a); 
11.    printf("b=%d",b); 
12.  
13.  return 0;
14.   
15. }

  Output:

1. a=13
2. b=12