c prog - initializing arrays question

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November 10th, 2002, 09:20 PM

cynsim

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c prog - initializing arrays question

I'm working on a problem that needs me to compare two strings together.

The problem is this, I'd like to be able to split up one of the strings so that I can put one word per array.

For example if the first string reads as such:

The brown cow ate grass.

I'd like to have an array for each of the words

word [0] = "The"
word [1] = "brown"

etc...

so that I can compare it to another string.
The data for both strings comes from a text file. Can anyone give me an idea on how to do this? Or maybe a better way to compare the two strings together?

Thanks ahead of time...

November 10th, 2002, 09:55 PM

Rdesign

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One word per array is no problem. One word per array Element is a different story. You might already know this but in C, a string is an array of char variables. So if you want to compare each element of a string you might try:

# include <iostream>
# include <cstring>
using namespace std;
int main() {
char st1[80] = "The brown cow chewed grass";
char st2[80] = "The brown cow ate grass";

for (int a=0; a<strlen(st1); a++) {
if (st1[a] != st2[a]) {
cout << "The strings are different!" << '\n';
return 0;
} else {
cout << "The strings are the same!" << '\n';
return 0;
}
}

I think that's right...at least close :-)

I hope this helps.

November 10th, 2002, 09:58 PM

cynsim

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yah I'm not sure how to get it so it will get just a word into the first array, then stop at the whitespace, increment the index, read the next word, put it in the array, increment again.

November 10th, 2002, 10:59 PM

TechNoFear

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I would use a pointer to the string and to the array element but simply

isspace() to find the spaces

Code:


for(i=0;i<lstrlen(sSentance);i++)
{
         if(!isspace(sSentance[i]))
                  //add to the array element lstrcat()
                
          if(isspace(sSentance[i]))
                  //alloc new word array element
                  //increment word array index
           
}

this is simpler using pointers

Code:

//this removes some punctuation from a string (to save the file name)
	char				sTempBuffer[L_STRING],sNewString[L_STRING],*pNew=NULL, *pOld=NULL;
	int					iLen=0;

	iLen=lstrlen(sBuffer);
	if(iLen>=L_STRING)
		return FALSE;//not enough space
	
	sprintf(sTempBuffer,"%s",sBuffer);
	pOld=sTempBuffer;
	pNew=sNewString;

	while(*pOld != '\0')
	{
		while(ispunct(*pOld))	*pOld++;
		while(isspace(*pOld))	*pOld++;
		*pNew++=*pOld++;
	}
	*pNew='\0';
	sprintf(sBuffer,"%s",sNewString);

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November 11th, 2002, 08:47 AM

ClayDowling

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If your stdc lib has the strsep function (which it probably won't unless you're running the latest GNU libc), that function is a miracle worker for breaking up a sentence on a common delimiter.

Barring that, I'd use the following C code:

Code:

char** word_list(char* sentence) {
  char** word;
  int wordcount = 0;
  char* pos = sentence;

  while(pos && *pos) {
    pos++;
    pos = strchr(pos, ' ');
    wordcount++;
  }

  word = (char**)calloc(wordcount + 1, sizeof(char*));
  
  wordcount = 0;
  pos = strtok(sentence, " ");
  while (pos) {
    word[wordcount++] = pos;
    pos = strtok(NULL, " ");
  }

  return word;

}

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November 12th, 2002, 02:01 PM

Rdesign

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New plan...

What do you think of using a multidimensional array?

Ex: // straray.cpp
// array of strings
#include <iostream>
using namespace std;

int main()
{
const int DAYS = 7; //number of strings in array
const int MAX = 10; //maximum size of each string
//array of strings
char star[DAYS][MAX] = { "Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday",
"Friday", "Saturday" };
for(int j=0; j<DAYS; j++) //display every string
cout << star[j] << endl;
return 0;

}
Does that give you any ideas?

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