[C]How to compare two strings w/o using strcmp()

dmail · 11-22-2005, 12:40 PM

ok then try it this way

Code:

	const int max_size = 20;
	char words[2][max_size] = {"program", "linux"};
	//print before we swap;
	printf("word one:%s\nword two:%s\n",words[0],words[1]);	
	char temp[max_size];
	strcpy(temp,words[0]);
	strcpy(words[0],words[1]);
	strcpy(words[1],temp);
	//print after we swap;
	printf("word one:%s\nword two:%s",words[0],words[1]);

kponenation · 11-22-2005, 12:42 PM

thank you dmail for your help but i can't include string.h so i can't use strcpy()
i know it would be a lot easier if i can but i just can't...

dmail · 11-22-2005, 12:46 PM

Quote:

Originally posted by kponenation
thank you dmail for your help but i can't include string.h so i can't use strcpy()
i know it would be a lot easier if i can but i just can't...

really? why cant you include "string.h"? the header is a standard c header isn't it?
in that case you cant use memcpy either.

looking at your earlier code

Code:

*word_array[i] = *word_array[i+1];

what this does is copy one char across and if you cant use string.h you may have to do this with 2d array for the lenght of the second index, to copy fully the string over.
another option is to create a struct string which looks something like

typedef struct tag_string
{
char* string;
int length;
}string,*p_string;

kponenation · 11-22-2005, 01:00 PM

i modified it like this
[CODE]int sort(char **word_array, int N ){
int i = 0;
int j = 0;
char *tmpArray[width];
int result;
while (i < N){
while(j < N-1){
result = compare_words(word_array[j], word_array[j+1]);
printf("%d",result);
if(result == 0){
tmpArray[j]= word_array[j];
word_array[j] = word_array[j+1];
word_array[j+1] = tmpArray[j];
}
j = j +1;}
i = i + 1;}
return 0;
}

i tested w/ 5 words
word_array[0] = sad
word_array[1] = toy
word_array[2] = doom
word_array[3] = send
word_array[4] = cotton

my result is
sad
doom
send
cotton
toy

jim mcnamara · 11-22-2005, 02:54 PM

This seems like homework. Oh well. If you can't USE strcmp, then WRITE strcmp so you can get on with it.

Code:

#include <stdlib.h>
typedef unsigned char uchar_t;

int
mystrcmp (p1, p2)
     void *p1;
     void *p2;
{
  uchar_t *s1 = (uchar_t *) p1;
  uchar_t *s2 = (uchar_t *) p2;
  uchar_t c1, c2;

  do
    {
      c1 = *s1++;
      c2 = *s2++;
      if (c1 == '\0')
	      break;
    } while (c1 == c2);

  return c1 - c2;
}

int compar(const void *a,const  void *b)
{
	return mystrcmp(a,b);
}

int main(int argc, char *argv[])
{
	char word[8][8]={
	         "dog"  ,
	         "cat"  ,
	         "house",
	         "child",
	         "zoo"  ,
	         "quick",
	         "animal",
	         "waste" };
	int i=0;
		
    qsort(word,8,8,compar);	          
	for(i=0;i<8;i++) printf("%s\n",word[i]);	          
    return 0;
}

kponenation · 11-22-2005, 02:56 PM

I know and i fixed it myself....
Thanks anyway for your help.

vivekr · 11-23-2005, 02:57 AM

Hai buddy--

What the hell is going on here?
If I've understood well what u r talking about then the problem is just a piece of cake. My code:

Code:

#include<stdio.h>
#include<string.h>
#include<malloc.h>

#define MAXLEN 20
#define STRINGS 5

int compStrings(char *x,char *y)
{
	unsigned int i;
	for(i=0;i<strlen(x) && i<strlen(y);i++)
	{
		if(x[i]>y[i])
			return 0;
		else if(x[i]<y[i])
			return 1;
	}
	if(i==strlen(x))
		return 1;
	return 0;
}

void sort(char **words)
{
	char *temp;
	int i=0,j,result;
	while(i<STRINGS)
	{
		j=i+1;
		while(j<STRINGS)
		{
			result=compStrings(words[i],words[j]);
			printf("%s %s result=%d",words[i],words[j],result);
			if(result==0)  /* words[i]>words[j] */
			{
				temp=words[i];
				words[i]=words[j];
				words[j]=temp;
			}
			j++;
		}
		i++;
	}
}

void main()
{
    char **WordList;
	int i;

	WordList=(char **) malloc(sizeof(char)*STRINGS);
	for(i=0;i<STRINGS;i++) 
	{
		WordList[i]=(char *) malloc(sizeof(char)*MAXLEN);
		printf("Enter the string %d",i);
		scanf("%s",WordList[i]);
	}

	sort(WordList);

	for(i=0;i<STRINGS;i++) 
		printf("\n %s",WordList[i]);	
}

The algorithm is not efficient. May be u can resort to quick and other types of sort if u need.

Send comments about the code

Cheers

kponenation · 11-23-2005, 08:29 AM

I've already fixed my code....
I was just missing a *