asked on

string comparison

//trying to compare a word from a string at specific position.
//steps involve:
//(Step 1) storing starting and ending address of words in arrays start_address[] and end_address[]
//(Step 2) retrieving substring from ch2 from the perticular position
//(Step 3) compairing substring ch3 with ch1.
//(Step 4) if equal strings then retun true else return false
//Now arrays contain starting and ending addresses.
//retrieve substring from the string ch2 is not working
//getting this error message
//error C2224: left of '.substr' must have struct/union type

//my problem can be solved by getting substring

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

int words ( char sentence[]);
int match ( char str[], char sentence[], int word_no);
int count_startaddress(int k, char sentence[]);
int find_startaddress( char str[], char sentence[], int word_no);
getsubstring(int);

int start_address[15];
int end_address[15];
char ch1[]="to";
char ch2[]="welcome to the robotics department of \n you";

char *ch3;//sub string
int indexe=0, indexs=0;

void main()
{
int tot, a;
int totalwords ;

int w_no = 1;
totalwords= words(ch2);

tot = match(ch1, ch2, w_no);
find_startaddress( ch1, ch2, w_no);

printf(" \n = %d" , tot);
if (tot == 0)
      printf("\n match is found");
else
      printf("\n match is not found");

for (a= 0 ; a<=totalwords-1 ; a++)
{
      printf("\n starting word %d = %d", a+1, start_address[a]);
      printf("\n ending word %d = %d", a+1, end_address[a]);

}

getsubstring(w_no);

getch();
}

getsubstring(int w_no)
{
//this part is not working

//*ch3.substr(start_address[3], end_address[3]-start_address[3]);


}

int words ( char sentence[])
{
      int i , wordcount=0 , length = strlen(sentence);

      for ( i=0 ; i<=length ; i++)

           if( sentence[i]==' '&& i!=0 || sentence[i]=='\0' )
            if( sentence[i-1]!=' ' && sentence[i-1]!='\t' && sentence[i-1]!='\n')
                       wordcount++;

      return wordcount ;
}

int match ( char str[], char sentence[], int word_no)
{
      int i , wordcount=0 , length = strlen(sentence);

      for ( i=0 ; i<=length ; i++)

           if( sentence[i]==' '&& i!=0 || sentence[i]=='\0' )
            if( sentence[i-1]!=' ' && sentence[i-1]!='\t' && sentence[i-1]!='\n')
                 {
                        wordcount++;
                        end_address[indexe++] = i;

                  }


      return wordcount ;
}

int count_startaddress(int k, char sentence[])
{

      int value = 0;
      int l;

      for (l=k; l>=0; )
      {

            //printf("\n value of l = %d and character = %c", k, sentence[l]);
            if(sentence[l] == ' ' && sentence[l+1] != ' ')
            {
                  value = l+2;
                  printf("\n value of l = %d and character = %c", l, sentence[l]);
                  break;
            }
            --l;
      }

      return value;
}

int find_startaddress( char str[], char sentence[], int word_no)
{
      int i , wordcount=0 , length = strlen(sentence);

      for ( i=0 ; i<=length ; i++)
      {
            if (i==0 && sentence[i]!=' ')
            {
                  start_address[indexs++] = 1;
            }

           if( sentence[i]==' '&& i!=0)
                  if( sentence[i+1]==' ' || sentence[i+1]=='\t' || sentence[i+1]!='\n' )
                 {

                        start_address[indexs++] = i+2;

                  }

      }
      return wordcount ;
}

graham_k

well, chr3 is a char *, but by using a dot operator, you are treatinmg it as a structure.

If
ch3.substr(h3.substr(start_address[3], end_address[3]-start_address[3]); , end_address[3]-start_address[3]);

means take a substring of ch3 starting at start_address[3] which is end_address[3]-start_address[3] bytes long, use

char *ch4;

strncpy(ch3, &ch3[start_address[3] ], end_address[3]-start_address[3]);

Take a look at strings.h, you'll find a bunch of useful string manipulation routines.

strncpy(dest, src, len) is used above; you might also want to look at strstr(string_to_search, look_for_this) to help you locate your substring, rather than for looping your way through.

In fact, I think that what you have written above could probably all be condensed into a few lines of code.

redgreenred

ASKER

char *ch4;

strncpy(ch3, &ch3[start_address[3] ], end_address[3]-start_address[3]);

I think you are trying to suggest this instead of above

char *ch4;

strncpy(ch4, &ch3[start_address[3] ], end_address[3]-start_address[3]);

graham_k

yes, sorry, the destination of strncpy() should have been the new varianble ch4.As I said, you can probably make the whole thing much simpler. But firstly, look into the string functions.

Here's a good URL for man pages http://www.linuxcentral.com/linux/man-pages/index.html

and here's one for strncpy() itself
http://www.opengroup.org/public/pubs/online/7908799/xsh/strncpy.html

go bak to the index & search for anything you want, or click on the link near the top of the page to learn all about string.h

ASKER CERTIFIED SOLUTION

nandi

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