Question

I need to compare strings from two text files. While separating the strings using strtok() (for either file), I have a problem while referring to sentences from two files, using strtok(), as they are colliding.

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

int main()
{
    FILE *fp,*fp1,*fp2;
    fp=fopen("inp1.txt","r");
    fp1=fopen("inp2t.txt","r");

    int f;
    char *a,*b,*chk;
    char buffer[500],buf[5000];

    while(fgets(buf,5000,fp1));
    {
        chk= (char *)strtok (buf," ");

        while(chk!=NULL)
        {
            rewind(fp);
            f=0;

            while(fgets(buffer,500,fp))
            {
                a= (char *) strtok(buffer,"\t");
                b= (char *) strtok(NULL,"\n");

                if(stricmp(a,chk)==0)
                {
                    printf("%s",b);
                    printf(" ");
                    f=1;
                }
            }

            if(f==0)
            {
                printf("%s",chk);
                printf(" ");
            }

            chk= (char *) strtok(NULL," ");                
        }
    }
    fclose(fp);
    fclose(fp1);

    getch();
    return 0;                    
}

How can I fix this code so that I’m able to extract tokens from both input files?

Answer 1

strtok() uses global internal values, which will collide. Use strtok_s() to prevent that, as that function takes a reference variable that will keep the two instances separate.