how can we update or delete the perticual record by using c language?

[AnagJohari]

I have a problem to update or delete the record from that file. so i request please send me the code of updating & deleting the record from the file......
please guys help me
thank you

[gpraghuram]

Hi,
R u maintaining the file like DB?
Can you give more details so that people can help u with ideas.

Raghu

[AnagJohari]

Hi,
R u maintaining the file like DB?
Can you give more details so that people can help u with ideas.

Raghu

ya you can say this i enter the information in the field
now i want to delete perticular record which we enter bt using fprintf() & fscanf() functions
ok i send you a code check it

#include<conio.h>
#include<stdio.h>
void main()
FILE *fp;
float price,value;
int number,quantity,i;
char item[10],filename[10];
printf("input file name\n");
scanf("%s",filename);
fp=fopen(filename,"w");
printf("Item name  Number  Price  Quantity\n");
for(i=1;i<=3;i++)
{
fscanf(stdin,"%s %d %f %d",item,&number,&price,&quantity);
fprintf(fp,"%s %d %.2f %d",item,number,price,quantity);
}
fclose(fp);
fprintf(stdout,"\n\n");
fopen(filename,"r");
printf("Item name  Number  Price  Quantity  value\n");
for(i=1;i<=3;i++)
{
fscanf(fp,"%s %d %f %d",item,&number,&price,&quantity);
value=price*quantity;
fprintf(stdout,"%-8s %7d %8.2f %8d 11.2%f\n",item,number,price,quantity,value);
}
fclose(fp);
}

now i want to delete any of one record which i enter from the above code please help me by making delete function so that i can delete a perticualar recode & also make a function of updation so that i can update any sort of record
i hope now you are getting what i want to tell you>

[donbock]

Your database file is implemented as a text file with each line being a different record. There is no assurance that all records are the same length. You cannot accomplish delete or update "in-place". You will have to accomplish these functions by making a modified copy of the database file.

delete algorithm:
Repeat for each line in the input file {
   Read the next line from the input file.
   If this is not the line to be deleted {
      Write the line to the output file.
      }
   }

update algorithm:
Repeat for each line in the input file {
   Read the next line from the input file.
   If this is not the line to be updated {
      Write the line to the output file.
      }
   Else {
      Modify the line as per the desired update.
      Write the modified line to the output file.
      }
   }

The last step for both cases is to replace the input file with the output file.

[nike111]

You cant delete as such from a text file..
try to maintain a fixd length for every record...
and search for the element you want to remove, leaving that, copy all the other records to another file "temp"
see if all records are copied , delete the existing one and rename the "temp" file

[AnagJohari]

Really tnx to give me a reply i try to understand this

[AnagJohari]

the one more problem is ocuured suppose i intialize 100 records in a file by giving null values or blankspaces or
0 for integer values
now i want to input 10 records inplace of intialize values
i m able to intialize the values in record
but not able to insert the value in place of intialize values
i send you a code plz check it & suggest me
i try very hard to do this but not succeed.

#include<conio.h>
#include<stdio.h>
 void display();
FILE *fp;
float cost,value;
int record,quantity,i;
char ToolName[10],filename[10];
void main()
{

printf("input file name\n");
scanf("%s",filename);
fp=fopen(filename,"r+");
printf("Item name  Number  Price  Quantity\n");
for(i=1;i<=3;i++)
{ ToolName[i]='0',record=0,cost=0,quantity=0;
//fscanf(stdin,"%s %d %f %d",ToolName,&record,&cost,&quantity);
fprintf(fp,"%s %d %.2f %d",ToolName,record,cost,quantity);

}

display();
rewind(fp);
fprintf(stdout,"%s %d %f %d \n",ToolName,record,cost,quantity);
while((fp,"%s %d %f %d",ToolName,&record,&cost,&quantity)!=0);
{
fscanf(stdin,"%s %d %f %d",ToolName,&record,&cost,&quantity);
fprintf(stdout,"%s %d %f %d \n",ToolName,record,cost,quantity);
}
fclose(fp);
display();
/*fp=fopen(filename,"r+");
rewind(fp);
while(fscanf(fp,"%s %d %f %d",ToolName,&record,&cost,&quantity)!=0);--->problem is here in while loop plz see this problem
{
fscanf(stdin,"%s %d %f %d",ToolName,&record,&cost,&quantity);
fprintf(fp,"%s %d %.2f %d",ToolName,record,cost,quantity);
}
display();*/
getch();
}
 void display()
{int i;
fprintf(stdout,"\n\n");
fopen(filename,"r");
printf("Item name  Number  Price  Quantity  value\n");
for(i=1;i<=3;i++)
{
fscanf(fp,"%s %d %f %d",ToolName,&record,&cost,&quantity);
//value=cost*quantity;
fprintf(stdout,"%s %7d %f %d \n",ToolName,record,cost,quantity);
}
fclose(fp);
}