Write program to swap 2 numbers

[HELP]

Write a C program to read two integers M and N and to swap
their values. Use a user defined functions for swapping. Output the values of M
and N before and after swapping with suitable message.

[harishmitty]

Iamgiving 2 versions of the same program ..


// Version-1: In this the swapped value(modified value)can be seen in the main method


#include<stdio.h>
#include<conio.h>


void swap(int *a,int *b)
{
int temp;
temp = *a;
*a = *b;
*b = temp;
}


void main()
{
int *p = 10;
int *q = 20;
clrscr();
printf("\n BEFORE SWAPPING :");
printf(" P = %d \t Q = %d",p,q);
swap(&p,&q);
printf("\n AFTER SWAPPING :");
printf(" P = %d \t Q = %d",p,q);
getch();
}


//Version 2: In this swapped value is not reflected in main function


#include<stdio.h>
#include<conio.h>


void swap(int *a,int *b)
{
int temp;
temp = *a;
*a = *b;
*b = temp;
}


void main()
{
int *p = 10;
int *q = 20;
clrscr();
printf("\n BEFORE SWAPPING :");
printf(" P = %d \t Q = %d",p,q);
swap(p,q);
printf("\n AFTER SWAPPING :");
printf(" P = %d \t Q = %d",p,q);
getch();
}


Watsthe diff b/w the two versions is ....


In version 1 , Iam sending address of the pointer to the function swap() as arguments .. Hence the pointers p & q are modified directly reflecting changed values when i print their values in main function..


In version 2,Iam just sending the pointers reference .. Hence the modified values aren't reflected in main function ..


Regards,


HARISH MITTY

[freshersen]

hi , am trying to swap(M,N) without using temp variable.


this is the question , i could attened the debuging context


#include<stdio.h>


void main()
{
int M = 5, N = 3;
printf("\nBefore Swap ");
printf("\n\tM=%d\tN=%d",M,N);

M = M + N;
N = M - N;
M = M - N;


printf("\nAfter Swap ");
printf("\n\tM=%d\tN=%d",M,N);
}

[madhab]

Hi I m trying to do it in a single line logic.


#include<stdio.h>


void main()
{
int M = 5, N = 3;
printf("\nBefore Swap ");
printf("\n\tM=%d\tN=%d",M,N);



M=N+(N=M)-M;



printf("\nAfter Swap ");
printf("\n\tM=%d\tN=%d",M,N);
}


Please verify.

[Jyoti Bhatnagar]

Hi,


As per question provided we have to use user defined function. So correct way could be as given by harishmitty using 3rd variable or as following


#include<stdio.h>


void main()
{
int M = 5, N = 3;


void swap (int m,int n);
printf("\nBefore Swap ");
printf("\n\tM=%d\tN=%d",M,N);
swap (M,N);


getch();


}
void swap(int m, int n)


{


m=m + n;
n = m - n;
m =m - n;


printf("\nAfter Swap ");
printf("\n\tm=%d\tn=%d",m,n);
}

[murari]

nice answers