Switching rows of two dimensional arrays in c - c

Question

At the moment I'm wondering how can I swap the values already in a two dimensional array, in this case I managed to swap them, however, I can't seem to be able to swap them back... How can I make a program swap the values back and forward for the array?
Code:
#include <stdio.h>
void main()
{
//declaration of values
int d = 0;
char value;
float list[5][6], swaplist[5][6];
float average_odd, sum = 0, average_even, sum1 = 0;
//Command list so that the user knows what he can do in this program
printf("Command list:\t \n\nCommand: \t\t Output: ");
printf("\n \"A\" \t\t Declare values of a list.\n \"O\" \t\t Obtain the average value of the even and odd column\n\t\t values in the list.\n");
printf(" \"I\" \t\t Exchange the values on the even columns with the odd ones.\n \"P\" \t\t Print the values of the list.\n \"S\" \t\t End program.");
//========================================================================================================
while (d != 1)
{
printf("\n\nInsert value: ");
scanf(" %c", &value);
//=========================================================================================================
if (value == 'a' || value == 'A')
{
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 6; j++)
{
printf("Insert value of element %d in column %d: ", i + 1, j + 1);
scanf("%f", &list[i][j]);
swaplist [i][j] = list[i][j];
}
}
}
//=========================================================================================================
if (value == 's' || value == 'S')
{
d++;
}
//=========================================================================================================
if (value == 'P' || value == 'p')
{
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 6; j++)
{
printf("%2.2f ", list[i][j]);
}
printf("\n");
}
}
//========================================================================================================
if (value == 'o' || value == 'O')
{
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 6; j = j + 2)
{
sum += list[i][j];
}
}
for (int i = 0; i < 5; i++)
{
for (int j = 1; j < 6; j = j + 2)
{
sum1 += list[i][j];
}
}
average_even = sum1 / 15;
printf("The average of the even columns = %.2f\n", average_even);
average_odd = sum / 15;
printf("The average of the odd columns = %.2f\n", average_odd);
}
//=======================================================================================================
if (value == 'i' || value == 'I')
{
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 6; j = j + 2)
{
list[i][j] = swaplist[i][j+1];
}
}
for (int i = 0; i < 5; i++)
{
for (int j = 1; j < 6; j = j + 2)
{
list[i][j] = swaplist[i][j - 1];
}
}
}
}
}

Answer 1

After swapping, you don't change the state of the swap list. At first, the swap list is a copy of the unswapped matrix. You don't change it to reflect the changes in the matrix and don't keep track of any other state.
You don't really need the swap list. I suggest that you just do a regular swapping of adjacent columns cell by cell:
if (value == 'i' || value == 'I') {
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 6; j = j + 2) {
float swap = list[i][j];
list[i][j] = list[i][j + 1];
list[i][j + 1] = swap;
}
}
}
That will toggle the matrix on repeated swaps.