Reordering numbers

**shaheel** · 11-22-2007

helllo guys. I'm having problem with this question:
Write a program in C involving the use of pointers to reorder a list of numbers so that any of the following arrangements can be carried out :

a) smallest to largest by magnitude
b) smallest to largest, algebraic (by sign)
c) largest to smallest, by magnitude
d) largest to smallest, algebraic

Here is my coding:

Code:

#include <stdio.h>
#include<math.h>

void main()
{
	int selection,count;
	float nums[10];

	printf("\n**************************MENU********************");
	printf("\n 1. reorder from smallest to largest, by magnitude");
	printf("\n 2. reorder from smallest to largest, algebraically");
	printf("\n 3. reorder from largest to smallest, by magnitude");
	printf("\n 4. reorder from largest to smallest, algebraically");
	printf("\n****************************************************");
	printf("\n Enter your selection please:");
	scanf("%d",&selection);

	
	for(count=0;count<=9;++count)
	{
		printf("\nEnter a number:");
		scanf("%d",&nums[count]);
	}

	switch (selection)
	{
	case 1:
		reorder1(nums);
		break;

	case 2:
		reorder2(nums);
		break;

	case 3:
		reorder3(nums);
		break;

	case 4:
		reorder4(nums);
		break;
	}
	getchar();
}
int reorder1(float nums[])
{
	float item,temp;
	int count,a;

	for (item=0;item<=9;++item)
	for (a=item+1;a<=9;++a)
	if(abs(nums[item])>abs(nums[a]))
	{
		temp=nums[item];
		(nums[item])=(nums[a]);
		(nums[a])=temp;
	}
	for (count=0;count<=9;++count)
	{
		printf("%f",nums[count])
		printf("\n");
	}
	return;
}

	int reorder2(float nums[])
{
	float item,temp;
	int count,a;

	for (item=0;item<=9;++item)
	for (a=item+1;a<=9;++a)
	if((nums[item])>(nums[a]))
	{
		temp=nums[item];
		nums[item]=nums[a];
		nums[a]=temp;
	}
	for (count=0;count<=9;++count)
	{
		printf("%f",nums[count])
		printf("\n");
	}
	return;
}	

	int reorder3(float nums[])
{
	float item,temp;
	int count,a;

	for (item=0;item<=9;++item)
	for (a=item+1;a<=9;++a)
	if(abs(nums[item])<abs(nums[a]))
	{
		temp=nums[item];
		nums[item]=nums[a];
		nums[a]=temp;
	}
	for (count=0;count<=9;++count)
	{
		printf("%f",nums[count])
		printf("\n");
	}
	return;
}	
int reorder4(float nums[])
{
	float item,temp;
	int count,a;

	for (item=0;item<=9;++item)
	for (a=item+1;a<=9;++a)
	if(nums[item]<nums[a])
	{
		temp=nums[item];
		nums[item]=(nums[a]);
		nums[a]=temp;
	}
	for (count=0;count<=9;++count)
	{
		printf("%f",nums[count])
		printf("\n");
	}
	return;
}

Im having about 30 errors while im trying to build the program...
Someone please help....

**Salem** · 11-22-2007

Yes, I get a lot of errors too

Code:

$ gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c:5: warning: return type of 'main' is not `int'
foo.c: In function `main':
foo.c:22: warning: int format, float arg (arg 2)
foo.c:28: warning: implicit declaration of function `reorder1'
foo.c:32: warning: implicit declaration of function `reorder2'
foo.c:36: warning: implicit declaration of function `reorder3'
foo.c:40: warning: implicit declaration of function `reorder4'
foo.c: In function `reorder1':
foo.c:52: warning: implicit declaration of function `abs'
foo.c:52: error: array subscript is not an integer
foo.c:54: error: array subscript is not an integer
foo.c:55: error: array subscript is not an integer
foo.c:61: error: parse error before "printf"
foo.c:63: warning: `return' with no value, in function returning non-void
foo.c: In function `reorder2':
foo.c:73: error: array subscript is not an integer
foo.c:75: error: array subscript is not an integer
foo.c:76: error: array subscript is not an integer
foo.c:82: error: parse error before "printf"
foo.c:84: warning: `return' with no value, in function returning non-void
foo.c: In function `reorder3':
foo.c:94: error: array subscript is not an integer
foo.c:96: error: array subscript is not an integer
foo.c:97: error: array subscript is not an integer
foo.c:103: error: parse error before "printf"
foo.c:105: warning: `return' with no value, in function returning non-void
foo.c: In function `reorder4':
foo.c:114: error: array subscript is not an integer
foo.c:116: error: array subscript is not an integer
foo.c:117: error: array subscript is not an integer
foo.c:123: error: parse error before "printf"
foo.c:125: warning: `return' with no value, in function returning non-void

> Someone please help.
Sure, you delete the source file and start again.
But before you sit down and try and "eat the whole elephant at one sitting", have a good read of this.
http://cboard.cprogramming.com/showthread.php?t=88495

Then consider a more measured approach where you
- write a bit
- compile it
- test it

Rather than this "big bang" approach you have at the moment.

**shaheel** · 11-22-2007

hahhaah.. ya thanks for ur advance

**Salem** · 11-22-2007

Well that really depends on whether you want to learn how to write programs doesn't it?

Smashing your face into the keyboard until you have a "complete" program, then trying to compile the result (and failing miserably), then posting the whole sorry mess on a message board for some other schmoe to debug for you is NOT a long term strategy.

So you may as well buckle down and learn how to write code in such a way that you can cope with whatever the compiler throws at you. This means learning the mantra of "compile often".

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