need help by "sorting an array of string"

Alexi_n · 05-09-2009, 11:49 AM

hi ...
i'm trying to sort an array of string.
my code should sort my array alphabetically [a-z] ,but it dos not do that ..

Code:

int main(void)

{
char mov[7][25];
int f,c,i; ///first , current , i-->char index 0-24;
int tmp,save[7]={0,1,2,3,4,5,6}; 
i=23;

strcpy(mov[0],"Cheaper by the Dozen 2");
strcpy(mov[1],"Drumline");
strcpy(mov[2],"Ever After");
strcpy(mov[3],"Cheaper by the Dozen");
strcpy(mov[4],"Mr. & Mrs. Smith");
strcpy(mov[5],"X-Men");
strcpy(mov[6],"Toy Story 2");
 

puts("<----before---->");
 for(i=0;i<7;i++)puts(mov[save[i]]);
puts("<--------------->"); 


 while(i>=0)
{
for(f=0;f<6;f++)
for(c=f+1;c<7;c++)
	{
	if(mov[f][i]<mov[c][i])
		{
		tmp=save[f];
		save[f]=save[c];
		save[c]=tmp;
		}
	}
i--;
}
puts("<-----after----->");
 for(i=0;i<7;i++)puts(mov[save[i]]);
puts("<--------------->");
return 0;
}

output :

<----before---->
Cheaper by the Dozen 2
Drumline
Ever After
Cheaper by the Dozen
Mr. & Mrs. Smith
X-Men
Toy Story 2
<--------------->
<-----after----->
Cheaper by the Dozen 2
Drumline
Mr. & Mrs. Smith
Ever After
X-Men
Cheaper by the Dozen
Toy Story 2
<--------------->
as you see in the output the string is not sorted .. i think, I'm missing something basic here...

PING · 05-09-2009, 01:37 PM

The order of your loops is jumbled up. I am not going to give you the code, but write some pseudocode which you should be able to follow

Code:

for i in range(0, numberofstrings)
 for j in range(0, numberofstrings-i-1)
  string1=arr[j]
  string2=arr[j+1]
  for k in range(0, min(size(string1), size(string2)))
   if string1[k] > string2[k]
    swap string1 and string2 and break
   else if string1[k] < string2[k]
    break

iMalc · 05-09-2009, 03:25 PM

Look at the way you're comparing items. For example, take just these two strings:

Code:

Drumline
Ever After

First you're comparing the first chars D and E and you make Drumline come first because D is less than E.
Then you're comparing the second chars r and v and again you make Drumline come first because r is less than v.
Then you're comparing the third chars u and e and now you make Ever After come first because e is less than u - WTF!

That's not how you order strings. Once you're compared the first characters and they are not the same then the rest of the characters are not relevant.
Of course that isn't the entire extent of the problems with that code, by far.

iMalc · 05-09-2009, 03:30 PM

Oh no wait, that outer loop is going backwards, and from only 7. It's actually not doing what I just said - It's far worse!

This code is stretching the limits of just how wrongly something can be done...

05-09-2009, 01:37 PM	#2
PING Registered User Join Date: Nov 2004 Location: india Posts: 493	The order of your loops is jumbled up. I am not going to give you the code, but write some pseudocode which you should be able to follow Code: for i in range(0, numberofstrings) for j in range(0, numberofstrings-i-1) string1=arr[j] string2=arr[j+1] for k in range(0, min(size(string1), size(string2))) if string1[k] > string2[k] swap string1 and string2 and break else if string1[k] < string2[k] break __________________ Go Petr !! My Blog
PING is offline

05-09-2009, 03:25 PM	#3
iMalc Algorithm Dissector Join Date: Dec 2005 Location: New Zealand Posts: 2,654	Look at the way you're comparing items. For example, take just these two strings: Code: Drumline Ever After First you're comparing the first chars D and E and you make Drumline come first because D is less than E. Then you're comparing the second chars r and v and again you make Drumline come first because r is less than v. Then you're comparing the third chars u and e and now you make Ever After come first because e is less than u - WTF! That's not how you order strings. Once you're compared the first characters and they are not the same then the rest of the characters are not relevant. Of course that isn't the entire extent of the problems with that code, by far. __________________ My homepage Advice: Take only as directed - If symptoms persist, please see your debugger
iMalc is offline

05-09-2009, 03:30 PM	#4
iMalc Algorithm Dissector Join Date: Dec 2005 Location: New Zealand Posts: 2,654	Oh no wait, that outer loop is going backwards, and from only 7. It's actually not doing what I just said - It's far worse! This code is stretching the limits of just how wrongly something can be done... __________________ My homepage Advice: Take only as directed - If symptoms persist, please see your debugger
iMalc is offline

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