Member Avatar for metal_butterfly

I have a program which will write informations like gid,gname,resname,restype,etc... in a file.I wrote a function to get the starting and ending position of a particular group.Stating of a particular group (say group 12)is denoted in a file by #gid12 and the end of the group is denoted by @gid12.I don't know wat mistake i have done. The code works correctly only for the 1st group in the file. when i try to get other groups information i am getting wrong output.Plz tel me wat is the bug in my program.And is there any other way to find the starting and ending position of a particular group from my file.

OUTPUT FILE WILL LOOK AS FOLLOWS:

IP_Address:
#gid1:sdf
Res-info$:;xyz;qww;qasddfasd;2:
Res-info$:;hjuy;asdfv;dfhvhvf;3:
Res-info$:;asdfg;eretg;wedsfh;7:
@gid1
IP_Address:
#gid2:dfc
Res-info$:;hjuy;asdfv;dfhvhvf;3:
Res-info$:;asdfg;eretg;wedsfh;7:
@gid2
IP_Address:
#gid12:xsdf
Res-info$:;xyz;qww;qasddfasd;2:
Res-info$:;asdfg;eretg;wedsfh;7:
@gid12

I have given the code below.Is there any other way to get the starting and ending position of a particular group from my file?? kindly help me on this

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<stdlib.h>
#define MAX 10
#define LINESIZE 256

struct resource
{
char res_type[12];
char res_name[25];
char res_loc[30];
int res_pri;
}res[MAX];
int store(char *ip_add,int g_id,char *g_name,struct resource res[],int n);

int FindStr(FILE *f, char *str);

main()
{
int g_id,i=0,choice,nor,j,status,gi=0,st=0,en=0;
char *g_name,*ip_add;
FILE *fp;



g_name=(char *)malloc(sizeof(char) * (MAX+1));
ip_add=(char *)malloc(sizeof(char) * (16));
printf("\nEnter the Following Data...\n");
printf("\nEnter Node IP Address:");
scanf("%s",ip_add);
printf("Enter g_id:");
scanf("%d",&g_id);
printf("Enter g_name:");
scanf("%s",g_name);
printf("Enter the resources...\n");

do
{
printf("Enter %d res_type:",i+1);
scanf("%s",res[i].res_type);

printf("Enter %d res_name:",i+1);
scanf("%s",res[i].res_name);

printf("Enter %d res_location:",i+1);
scanf("%s",res[i].res_loc);

printf("Enter %d res_priority:",i+1);
scanf("%d",&res[i].res_pri);


printf("\nDo u want to add another resource?\n 1.Yes\n2.N0\n:");
scanf("%d",&choice);

i++;
}while(choice==1);
nor=i-1;
j=0;


status=store(ip_add,g_id,g_name,res,nor);
if(status==0)
printf("\nfile updated successfully...\n");
else
printf("\nUpdate failed...\n");

 const char sbase[] = "#gid";
 const char ebase[] = "@gid";
 char start [10],end[10];
 //read the group id to be fetched
 printf("Enter the Group id to be fetched:");
 scanf("%d",&gi) ;
 sprintf(start, "%s%d", sbase, gi);
 printf("start = \"%s\"\n", start);
 sprintf(end, "%s%d", ebase, gi);
 printf("end = \"%s\"\n", end);
 fp=fopen("config.ini","r");

 st=FindStr(fp, start);
 en=FindStr(fp, end);
 printf("\nStart position:%d",st);
 printf("\nEnd position:%d",en);




}


struct group
{
char ip_add[25];
int g_id;
char g_name[25];
struct resource res[];
}g;

int store(char *ip_add,int g_id,char *g_name,struct resource res[],int n)
{
FILE *fp;
int i=0,j=0;
//ip_add=(char *)malloc(sizeof(char) * (MAX+1));
fp=fopen("config.ini","a");
if (fp==NULL)
{
printf("cannot open file");
return 1;
}
else
{
strcpy(g.ip_add,ip_add);
g.g_id=g_id;
strcpy(g.g_name,g_name);

while(i<=n)
{
//g.res[i].res_type=res[i].res_type;
strcpy(g.res[i].res_type,res[i].res_type);
strcpy(g.res[i].res_name,res[i].res_name);
strcpy(g.res[i].res_loc,res[i].res_loc);
g.res[i].res_pri=res[i].res_pri;
i++;
}



fprintf(fp,"\nIP_Address:%s",g.ip_add);
fprintf(fp,"\n#gid%d:",g.g_id);
fprintf(fp,"%s",g.g_name);

while(j<=n)
{
fprintf(fp,"\nRes-info$:;");
fprintf(fp,"%s;",g.res[j].res_type);
fprintf(fp,"%s;",g.res[j].res_name);
fprintf(fp,"%s;",g.res[j].res_loc);
fprintf(fp,"%d:",g.res[j].res_pri);
j++;
}
fprintf(fp,"\n@gid%d",g.g_id);
fclose(fp);
return 0;
}


}


int FindStr(FILE *f, char *str)
{
 int s_pos; //string position in the text
 int c_pos; //char position in the text
 char *string;
 char ccnt; //char count
 
 s_pos = -1;
 c_pos = 0;
 string = malloc(strlen(str));
 while (!feof(f))
  {
   if (c_pos == 0)
    for (ccnt = 1; ccnt <= strlen(str); ccnt++)
     if (!feof(f))
      string[ccnt - 1] = getc(f);

   if (c_pos != 0)
    if (!feof(f))
     {
      for (ccnt = 0; ccnt <= strlen(str) - 2; ccnt++)
       string[ccnt] = string[ccnt + 1]; 
      string[strlen(str) - 1] = getc(f);
     }  
   if (strcmp(string, str) == 0)
    {
     s_pos = c_pos;
     break;
    }   
   c_pos++;
  }
 return(s_pos);
}
  • 2 Contributors
  • 1 Reply
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  • 8 Hours Discussion Span
  • Latest Post Latest Post by jephthah

Dani AI

Generated

The symptom (works for the first group but not later ones) points to buffer/EOF/offset bugs in the custom FindStr routine rather than the file format. The routine appears to read raw bytes into a buffer without reserving space for a terminating '\0', uses getc into a char (loses EOF), relies on feof as a loop condition, and returns a count of sliding-window iterations rather than a reliable byte offset. Those problems make comparisons with strcmp undefined and make subsequent matches unreliable.

A simple, robust approach is to scan the file line-by-line and use strncmp/strstr to detect the marker lines; compute the byte offset with ftell (or keep a running offset). This avoids tricky manual sliding-window logic and handles whole lines at once. Example pattern:

long find_marker_pos(FILE *f, const char *marker)
{
    char line[512];
    while (fgets(line, sizeof line, f)) {
        if (strncmp(line, marker, strlen(marker)) == 0)
            return ftell(f) - (long)strlen(line); /* start of this line */
    }
    return -1; /* not found */
}

If both start and end positions are needed, either (a) search once and record the first start then the first end after that, or (b) call this function twice but always rewind the file first.

Notes and cautions:

  • Check all return values (fopen, fgets, ftell). Always handle NULL/EOF results.
  • On Windows text mode, ftell can be affected by CR/LF translation; open with "rb" if you need exact byte offsets across platforms.
  • Prefer size_t/int for counters, and use int ch = getc(f) if you do character reads so EOF is detected correctly.
  • See the standard references for behavior: fgets reference and ftell reference.

This advice addresses the core issues in your posted routine and gives a safe replacement strategy that will work for any numbered group, not just the first. Also, is right — posting once is enough.

Member Avatar for jephthah

please stop double posting your question.

you will not get twice the number of answers. you will, in all likelihood, get fewer answers because people find double posters to be annoying.

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