double m[3][3];

for (i=0; i<ROWLENGTH; ++i){
  double temp;
  temp = m[r2][i];
  m[r2][i] = m[r1][i];
  m[r1][i] = temp;
}

double **m;
m = malloc(sizeof(double*)*NUMROWS);
/* put error checking here */
for (i=0; i<NUMROWS; ++i){
  m[i] = malloc(sizeof(double)*ROWLENGTH);
  /* error checking again */
}

double *temp;
temp = m[r2];
m[r2] = m[r1];
m[r1] = temp;

double r[3], q[3] = { 1, 2, 3 };
r = q; /* ERROR */

typedef struct { double r[ROWLENGTH] } row;
row m[NUMROWS] = { {1, 2, 3}, {4, 5, 6}, {7, 8 9}};

row temp = m[2];
m[2] = m[1];
m[1] = temp;

typedef int Row[3];
Row Matrix[3];

Row Temp;

memcpy(Temp, Matrix[0], sizeof(Row));
memcpy(Matrix[0], Matrix[1], sizeof(Row));
memcpy(Matrix[1], Temp, sizeof(Row));

int x[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

for (int i=0; i<3; i++) {
    int temp = x[0][i];
    x[0][i] = x[1][i];
    x[1][i] = temp;
}

typedef struct {int m[3];} Row;
typedef int RowAccess[3];

main()
{
  Row tmp,row[]={{1,2,3},{4,5,6},{7,8,9}};
  RowAccess *rowa=row;
  tmp=row[0];
  row[0]=row[1];
  row[1]=tmp;
  /* easy access to matrix here: (is this what you want?) */
  rowa[0][0]=0;
  rowa[0][1]=1;
  ...
  return 0;
}

auxiliary = a ;
a = b ;
b = auxiliary ;

a ^= b ;
 b ^= a ;
 a ^= b ;

int swap (int *a , int *b){
    (*a)^=(*b);
    (*b)^=(*a);
    (*a)^=(*b);
    return 0;
}

#define ROW_COUNT 5
#define COLUMN_COUNT 5
....
int a[ROW_COUNT][COLUMN_COUNT];

printf("nSwap Row: "); scanf("%d", &swp1) ; // first row index
printf("With Row: "); scanf("%d", &swp2);    // second row index

for (j = 0 ; j < COLUMN_COUNT ; j++){
     swap(  &a[swp1][j] , &a[swp2][j] );
}

#include "stdio.h"
#include "conio.h"

#define ROW_COUNT 5
#define COLUMN_COUNT 5



int swap (int *a , int *b){
        (*a)^=(*b);
        (*b)^=(*a);
        (*a)^=(*b);
        return 0;

}

int main(){
    int i, j ;
    int swp1, swp2 ;
    int a[ROW_COUNT][COLUMN_COUNT];

    // Create ( ROW_COUNT X COLUMN_COUNT ) random matrix

    for (i = 0 ; i < ROW_COUNT ; i++ )
        for (j = 0 ; j < COLUMN_COUNT ; j++ )  a[i][j] = rand();

    // Display matrix before row swap

    for (i = 0 ; i < ROW_COUNT ; i++ ){
        for (j = 0 ; j < COLUMN_COUNT ; j++ )  printf("%dt",a[i][j]);
        printf("n");
    }

    // Elements to be swapped

    printf("nSwap Row: "); scanf("%d", &swp1) ;  // first row index
    printf("With Row: "); scanf("%d", &swp2);     // second row index

    // Swapping right here

    for (j = 0 ; j < COLUMN_COUNT ; j++){
         swap(  &a[swp1][j] , &a[swp2][j] );
    }


    // Display once again

    printf("n");
    for (i = 0 ; i < ROW_COUNT ; i++ ){
        for (j = 0 ; j < COLUMN_COUNT ; j++ )  printf("%dt",a[i][j]);
        printf("n");
    }



    getch();
 return 0;
}

temprow = row[1];
row[1] = row[0];
row[0] = temprow;

#include <algorithm>
int A[][] = {{1,2,3},{4,5,6},{7,8,9}};
swap(A[0],A[2]); //swaps first and last row