Thread: bubble sort

Hello everyone, I have a program where I have to sort array of structures by the month of the birthday. I have a function to do that and it looks that it must work but the program stops when it comes to that function. I will be very appriciated if someone can tell me where i am wrong.
Thank you

Here is the function, I am using bubble sort.

Code:

void sort_array_by_month(void)
{
	struct sStudent Temp;
	int i, n, swap;

	do
	{
		swap=0;
		for(i=0; i<3; ++i)//bubble sort
		{
			if(Algebra[i].birthday.month>Algebra[i+1].birthday.month)
				Temp.birthday.month=Algebra[i].birthday.month;   // temp[Count]=Array[count+1]
				Temp.birthday.day=Algebra[i].birthday.day;
				Temp.birthday.year=Algebra[i].birthday.year;

				for(n=0; Algebra[i].first_name[n]!=0; ++n)
				{
					Temp.first_name[n]=Algebra[i].first_name[n];
					Temp.first_name[n]='\0';
				}
				
				for(n=0; Algebra[i].last_name[n]!=0; ++n)
				{
					Temp.last_name[n]=Algebra[i].last_name[n];
					Temp.last_name[n]='\0';
				}

				Algebra[i].birthday.day=Algebra[i+1].birthday.day; //Array[Count]=Array[Count+1]
				Algebra[i].birthday.month=Algebra[i+1].birthday.month;
				Algebra[i].birthday.year=Algebra[i+1].birthday.year;

				for(n=0; Algebra[i].first_name[n]!=0; ++n)
				{
					Algebra[i].first_name[n]=Algebra[i+1].first_name[n];
					Algebra[i].first_name[n]='\0';
				}
				
				for(n=0; Algebra[i].last_name[n]!=0; ++n)
				{
					Algebra[i].last_name[n]=Algebra[i+1].last_name[n];
					Algebra[i].last_name[n]='\0';
				}
				
				Algebra[i+1].birthday.month=Temp.birthday.month;  //Array[Count+1]=Temp
				Algebra[i+1].birthday.day=Temp.birthday.day;
				Algebra[i+1].birthday.year=Temp.birthday.year;

				for(n=0; Algebra[i].first_name[n]!=0; ++n)
				{
					Algebra[i+1].first_name[n]=Temp.first_name[n];
					Algebra[i+1].first_name[n]='\0';
				}
				
				for(n=0; Algebra[i].last_name[n]!=0; ++n)
				{
					Algebra[i+1].last_name[n]=Temp.last_name[n];
					Algebra[i+1].last_name[n]='\0';
				}

				swap=1;	
		}
	}while(swap!=0);
	
}

You're working very hard at this, clearly.

You don't need to work anywhere near this hard.

Structures have the "magical" property in C, of being able to be swapped, as a whole unit. That works using either a pointer to the struct being swapped, OR it works by swapping it out *directly*.

No further struct members need to even be mentioned! Your bubblesort shrinks by a factor of 10X.

If temp is a struct of the same type, (or a pointer to that kind of struct), then

Code:

temp = struct1;
struct1 = struct2;
struct2 = temp;

works.

And you can thank iMalc for that tip.

thank you for the tip I'll try to get it work, I kind of thought that it must be something more simple to sort it but our teacher told that when you sort array of structures you have to do it in the way how I did it. And thanks again

Adak I need to sort it only by the month of the birthday, I do not know if i've done this right but here is the updated version.

Code:

#include<stdio.h>

struct sdate
{
	int month;
	int day;
	int year;
};

struct sStudent
{
	char last_name[30];
	char first_name[30];
	struct sdate birthday;
}Algebra[10];


void get_first_name(int j)
{

	printf("First name    ");
	scanf("%s", Algebra[j].first_name);
}

void get_last_name(int j)
{

	printf("Last name     ");
	scanf("%s", Algebra[j].last_name);
}

void get_date_of_birth(int j)
{
	printf("Birthday      ");
	scanf("%i%i%i", &Algebra[j].birthday.day, &Algebra[j].birthday.month, &Algebra[j].birthday.year);
	printf("\n");
}
int get_info(void)
{
	int i;
	
	printf("!!! Date of Birth must be entered as dd mm yy separated by space\n\n");

	for(i=0; i<3; ++i)
	{
		printf("Student# %i\n", i+1);
		printf("========================\n");
		
		get_first_name(i);
		get_last_name(i);
		get_date_of_birth(i);
	}
	return 0;
}

void sort_array_by_month(void)
{
	struct sStudent Temp;
	int i, n, swap;

	do
	{
		swap=0;
		for(i=0; i<3; ++i)//bubble sort
		{
			if(Algebra[i].birthday.month>Algebra[i+1].birthday.month)
				
				Temp=Algebra[i];
				Algebra[i]=Algebra[i+1];
				Algebra[i+1]=Temp;

				swap=1;	
		}
	}while(swap!=0);
	
}

 main()
{
	int i;

	get_info();
	sort_array_by_month();

	for(i=0; i<3; ++i)
	{
		printf("%s  %s", Algebra[i].first_name, Algebra[i].last_name);
		printf("%15i/%i/%i\n", Algebra[i].birthday.day, Algebra[i].birthday.month, Algebra[i].birthday.year);
	}

}

Also not sure but do I need to end string with a null character maybe like

Code:

Temp.first_name[n]='\0';
Temp.last_name[n]='\0';    and so on

Thank you for your help!!!

If you are handling strings in a very rigid fixed field length, then you don't need an end of string char - '\0' (note the single quotation marks.

If you are using any string functions in your code, you'll need end of string char's in place.

strcmp(), strlen(), strcpy(), and printf("%s"), etc., all rely on strings being present. Only char's with an end of string marker in place, are seen as strings, by C.

You're welcome.

Thank you guy's, you are the best.