C programming help for beginner sort routine

Greetings all. I had been trying to learn C Programming but have not gotten very far. Anyway, my son is trying to get a program to work but is having trouble. I received excellent help last time and I am hoping I can get more.

The included code is supposed to have the following parameters:

The user enters 5 numbers.
The code checks for a duplicate entry.
The code sorts the numbers in ascending order.

I know enough to know that the code could be much more compact with the use of better arrays and loops, however, the coding shown is what my son was instructed to use at this level of learning. According to my son, the Duplicates check works, but the sort does not. If the following is entered:

5,4,3,2,1

The output is:

2,1,3,4,5

I am at a loss and I am unable to run the code to try to help as I do not have a compiler and the ones I try on-line all report errors, even though my son does not get any. Not sure what he is using. Anyway, I am hoping someone can spot the mistake and help out. Once it is working, maybe someone can show how it could be done more efficiently.

#include <stdio.h>

int TheDupe(double mark[]);
void order(double mark[]);

int main(void){

	double a, b, c, d, e, mark[5];
	
	int x;

	printf("Please enter 5 numbers. They can be positive or negative. No duplicates please.\n");
	printf("Value 1=> ");
	scanf_s("%lf", &a);
	printf("Value 2=> ");
	scanf_s("%lf", &b);
	printf("Value 3=> ");
	scanf_s("%lf", &c);
	printf("Value 4=> ");
	scanf_s("%lf", &d);
	printf("Value 5=> ");
	scanf_s("%lf", &e);

	mark[0] = a;
	mark[1] = b;
	mark[2] = c;
	mark[3] = d;
	mark[4] = e;

	order(mark);

	x = TheDupe(mark);

	if (x = 1)
		printf("%d Duplicates detected! You are a failure at following even the simplest\ndirections.\n", x);
	
	if (x = 0)
		printf("%d The ascending order of the numbers you've entered is %f\n%f\n%f\n%f\n%f\n", x, mark[0], mark[1], mark[2], mark[3], mark[4]);
	
	return(0);
}

void order(double mark[]){

	double temp;
	int x;
	int y;
	int z;

	for (int i = 1; i<5; i++){
		if (mark[0] > mark[i]){
			temp = mark[0];
			mark[0] = mark[i];
			mark[i] = temp;
		}
		for (int i = 2; i<5; i++){
			if (mark[1] > mark[i]){
				temp = mark[1];
				mark[1] = mark[i];
				mark[i] = temp;
			}
			for (int i = 3; i<5; i++){
				if (mark[2] > mark[i]){
					temp = mark[2];
					mark[2] = mark[i];
					mark[i] = temp;
				}
				for (int i = 4; i<5; i++){
					if (mark[3] > mark[i]){
						temp = mark[3];
						mark[3] = mark[i];
						mark[i] = temp;
					}
				}
			}
		}
	}
}

int TheDupe(double mark[]){

	int x = 0;

	for (int i = 0; i < 4; i++) {
		for (int j = i + 1; j <= 4; j++) {
			if (mark[i] == mark[j]){
				x = 1;
				return (x);
			}
		}
	}
	return(x);
}

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