program that deletes same lines in a text file

[ferronia]

Hello. I am working on a program that deletes same lines in a text file.

I already wrote it, but it still doesn't work. Could you please help me to find the mistake?

Thank you.

#include <stdio.h>
main(){
           FILE *f1,*f2;
           char oneword[100],filename[25];
           int c;
           long int i,j;
           char *norstring[500000];  /* I count from 1 */
           long int currentLength=0;
           i=0;
           
           printf("enter filename of the first file -> ");
           scanf("%s",filename); /* read the desired filename */
           f1 = fopen(filename,"r");

           int t;
           
           
           do {
           i=i+1;
           c = fscanf(f1,"%s",oneword); /* got one word from the 1st file */

           if(i==1){
                    norstring[1]=oneword;
                    currentLength=1;
                    }

                    
           
           
           
           if((c==1) && (i>1)){

                t=0;
                for(j=1;j<=currentLength;j++){
                                   if(norstring[j]==oneword){
                                                            t=1;
                                                            }
                                              }
                
                
                if(t==0){
                         currentLength++;
                         norstring[currentLength]=oneword;
                         }
                         
                               }

           }while (c != EOF && i<=(500000)); /* repeat until EOF */
           fclose(f1);


           f2 = fopen("file9.txt","w");

           for(j=1;j<=currentLength;j++){
                                         fprintf(f2,norstring[j]); /* prints it to the file */
                                         fprintf(f2,"\n");
                                         }
           fclose(f2);
           printf("\n\ndone. file9.txt created. press any key");
           getch();       
       }

[AndiPersti]

norstring[1]=oneword;
...
norstring[currentLength]=oneword;

Do you understand that you are always assigning the same pointer to all elements of your array?

Bye, Andreas

[ferronia]

Hi, I have no clue about pointers. I only know how to make an array and I am used to other programing languages (Pascal).. For me norstring[1] is just the first string in my array. How can I correct it?

[Malcolm McLean]

You're going about the program in the wrong way.

You need to read it in a line at a time with fgets(). For now, set the buffer to 1024 bytes and assume that no line will be longer than that.

Then think about the logic. For a first attempt, assume a fixed limit on the number of lines. Then look up malloc() and see if you can remove that fixed limit (hint, go through the file for a first pass).