Finding a integer in a file

Laika1986

Hey guys I am working on a assignment for next week, basically I have to create a structure for an employee database. Everything is running fine in the code its step two that is wrecking my head! If the employee identification number is already in the file I have to produce an error. I cant think how to do this, i have researched fread but i tried using it to no avail! I'm not looking for code help here more so advice on what to use!I'll post my code so you can have a better understanding

#include <stdio.h>

int main()
{

	FILE *fp, *fp2;
	


	struct info{
		char first_name[16];
		char last_name[16];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		}id;
		
		printf("Please enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		printf("Please enter First name: ");
		fgets(id.first_name,16,stdin);
		printf("Please enter Last name: ");
		fgets(id.last_name,16,stdin);
		printf("Please enter hours worked: ");
		scanf("%d",&id.hours);
		printf("Please enter rate of pay: ");
		scanf("%f",&id.rate);
		printf("Please enter rate of tax: ");
		scanf("%f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		fp=fopen("employee.dat","a");
		fprintf(fp,"\nID Number: %d\n",id.identification);
		fprintf(fp,"First Name: %s",id.first_name);
		fprintf(fp,"Last Name: %s",id.last_name);
		fprintf(fp,"Hours Worked: %d\n",id.hours);
		fprintf(fp,"Rate of Pay: %.2f\n",id.rate);
		fprintf(fp,"Rate of Tax: %.2f\n",id.tax);
		fprintf(fp,"Gross Pay: %.2f\n",id.gross);
		fprintf(fp,"Net Pay: %.2f\n",id.net);
		
		fp2=fopen("employee.dat","r");		
		
		
		
return 0;
}

Kidchameleon

What kind of file are you reading from? I just ripped some code from a program of mine that reads from a text file and converts the text to integer, perhaps it will help...

#include <stdio.h>
#include <stdlib.h>
#include <sstream>
#include <iostream>
#include <string>
#include <fstream>

ifstream myFile;

myFile.open("aFile.txt");

string data;

int intVal = 0;



getline(myFile, data, ','); //my file is comma delimited, yours is probably different

intVal = atoi(data.c_str()); now you can compare intVal to the other id numbers for any matches

amen

minor item but your struct as your ID as the third element but you write ID to the file in the first position.

While not wrong this is just bad practice. The file write/read order should match the struct. Makes life a lot easier when debugging.

Laika1986

Kidchameleon wrote: »

What kind of file are you reading from? I just ripped some code from a program of mine that reads from a text file and converts the text to integer, perhaps it will help...

#include <stdio.h>
#include <stdlib.h>
#include <sstream>
#include <iostream>
#include <string>
#include <fstream>

ifstream myFile;

myFile.open("aFile.txt");

string data;

int intVal = 0;



getline(myFile, data, ','); //my file is comma delimited, yours is probably different[B]What do you mean by comma delimited!?[/B]

intVal = atoi(data[B].c_str())[/B]; now you can compare intVal to the other id numbers for any matches

I am reading from a .dat file. I was thinking about it last night and i intended to try using atoi! Ill mess around with what you provided(thanks very much by the way!) My only confusion are the parts i have bolded. Could you explain them to me?

@amen

Thanks for the tip. I removed it yesterday evening as I wanted to figure out how to pass the structure to a function. I am going to post my new code below as it wont compile i get an error "incompatiable type when assigning type File from type struct, can anyone help me on this?

#include <stdio.h>

	
	struct info{
		char first_name[16];
		char last_name[16];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		};
		
		typedef struct info next;
		
		next DataReceive(next id);
		
		main(void)
		{
		
		
		next id;
		id= DataReceive(id);
		
		return 0;
		}
		
		next DataReceive(next id)
		{
		FILE *fp,fp2;
		printf("Please enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		printf("Please enter First name: ");
		fgets(id.first_name,16,stdin);
		printf("Please enter Last name: ");
		fgets(id.last_name,16,stdin);
		printf("Please enter hours worked: ");
		scanf("%d",&id.hours);
		printf("Please enter rate of pay: ");
		scanf("%.2f",&id.rate);
		printf("Please enter rate of tax: ");
		scanf("%.2f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		fp=fopen("employee.dat","a");
		fprintf(fp,"\nID Number: %d\n",id.identification);
		fprintf(fp,"First Name: %s",id.first_name);
		fprintf(fp,"Last Name: %s",id.last_name);
		fprintf(fp, "Hours Worked: %d\n",id.hours);
		fprintf(fp,"Rate of Pay: %.2f\n",id.rate);
		fprintf(fp,"Rate of Tax: %.2f\n",id.tax);
		fprintf(fp,"Gross Pay: %.2f\n",id.gross);
		fprintf(fp,"Net Pay: %.2f\n",id.net);
		
		fp2=fopen("employee.dat","r");		
		
		return id;
		}

Someday I am looking forward to being able to help on here not just look for answers!!

Kidchameleon

Comma delimited basically means that each piece of data in the file is separated by a comma:

23,44,12,66,764

So the program knows when it reaches a comma that it has all of that particular piece of data and that it can move onto the next. You dont necessarily have to use a comma either, you could use any character or string as a "delimiter" (Google that word).



The c_str() method turns a string into a cstring. The atoi function requires a cstring to work. When we read in the file, we are reading strings as opposed to cstrings so the conversion is required.

string and cstring are basically the same thing but one is part of the standard language and the other is part of MFC. (Google MFC, your going to come across that allot)

Laika1986

Kidchameleon thanks for your reply, I didn't have much time over the weekend to reply. I have researched what you suggested and am on the right track however the only problem im coming across is when i print the variables first and last name to the file it skips a line. I have tried loads of different combinations for this but i can't seem to get it in sync. I am presuming this is somehow caused by fgets?

Kidchameleon

Laika1986 wrote: »

Kidchameleon thanks for your reply, I didn't have much time over the weekend to reply. I have researched what you suggested and am on the right track however the only problem im coming across is when i print the variables first and last name to the file it skips a line. I have tried loads of different combinations for this but i can't seem to get it in sync. I am presuming this is somehow caused by fgets?

Try removing the "\n" from any write statements. This adds a new line to any output.

Laika1986

Kidchameleon wrote: »

Try removing the "\n" from any write statements. This adds a new line to any output.

I tried that, there's no "\n" in the program at all however here is what it produces

ID Number: 1651656,First Name: Super 
,Last Name: Man
, Hours Worked: 40,Rate of Pay: 8.65,Rate of Tax: 12.75,Gross Pay: 346.00,Net Pay: 301.89,

Kidchameleon

Laika1986 wrote: »

Kidchameleon wrote: »

Try removing the "\n" from any write statements. This adds a new line to any output.

I tried that, there's no "\n" in the program at all however here is what it produces

ID Number: 1651656,First Name: Super 
,Last Name: Man
, Hours Worked: 40,Rate of Pay: 8.65,Rate of Tax: 12.75,Gross Pay: 346.00,Net Pay: 301.89,

Could you post your code as is and ill have a look im afc at the moment

Laika1986

Kidchameleon wrote: »

Could you post your code as is and ill have a look im afc at the moment

#include <stdio.h>
#include <stdlib.h>



int main()
{

	FILE *fp, *fp2;
	fp2=fopen("employee.dat", "r");
	


	struct info{
		char first_name[16];
		char last_name[16];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		}id;
		
		printf("Please enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		printf("Please enter First name: ");
		fgets(id.first_name,16,stdin);
		printf("Please enter Last name: ");
		fgets(id.last_name,16,stdin);
		printf("Please enter hours worked: ");
		scanf("%d",&id.hours);
		printf("Please enter rate of pay: ");
		scanf("%f",&id.rate);
		printf("Please enter rate of tax: ");
		scanf("%f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		fp=fopen("employee.dat","w");
		fprintf(fp,"ID Number: %d,",id.identification);
		fprintf(fp,"First Name: %s,",id.first_name);
		fprintf(fp,"Last Name: %s, ",id.last_name);
		fprintf(fp,"Hours Worked: %d,",id.hours);
		fprintf(fp,"Rate of Pay: %.2f,",id.rate);
		fprintf(fp,"Rate of Tax: %.2f,",id.tax);
		fprintf(fp,"Gross Pay: %.2f,",id.gross);
		fprintf(fp,"Net Pay: %.2f,",id.net);
		
		fp2=fopen("employee.dat","r");		
		
		
		
return 0;
}

Thanks again whenever you get a chance no rush

Cork24

ok just had a look at your Code.

first off where is your
"namespace std;" ??


Second you are Opening


fp2=fopen("employee.dat", "r");I take it you are using Pointers ?

if so can i see the
#include <stdio.h>
#include <stdlib.h>Code if you have...

Where is your Loop to Read the Files,

Look up Random Access File System, When i get home i can Upload a Bubble Sort Code that will Sort out the Array which is alot easier to search when looking for ID number.

I have a Random Access Codes at home i will post when i get a chance.

ressem

You're retrieving the first and last names using fgets, which keeps the newline (unless you type 15 chars for the firstname and/or lastname).

So you'll want to check whether the character array ends in a newline + null, and write another null over the newline character.

Laika1986

ressem wrote: »

You're retrieving the first and last names using fgets, which keeps the newline (unless you type 15 chars for the firstname and/or lastname).

So you'll want to check whether the character array ends in a newline + null, and write another null over the newline character.

Ah yes i thought that might have been the problem. So basically if name[16]=='\n' name[16]=='\0'???in a while i should have said!

Laika1986

Cork24 wrote: »

ok just had a look at your Code.

first off where is your
"namespace std;" ??


Second you are Opening


fp2=fopen("employee.dat", "r");I take it you are using Pointers ?

if so can i see the
#include <stdio.h>
#include <stdlib.h>Code if you have...

Where is your Loop to Read the Files,

Look up Random Access File System, When i get home i can Upload a Bubble Sort Code that will Sort out the Array which is alot easier to search when looking for ID number.

I have a Random Access Codes at home i will post when i get a chance.

I didnt intend to use pointers but are they necessary?Im not gonna lie either iv never heard of namespace.std, ill search it now and RAC. Is the loop you speak of just to keep re-entering data?Thanks for the help lads

Cork24

RAC is what you use when you need to open, read, write and close a file,

Random access places the data inside the text file as they are entered so I could have a student list of 1,5,2,7,6 etc un-sorted data file



You will need a loop that searches each data inside your text file

So if your search finds a Id number it will then print it out if not it will go to the next section of your program,

An will allow you to enter data using that ID number

ressem

Laika1986 wrote: »

Ah yes i thought that might have been the problem. So basically if name[16]=='\n' name[16]=='\0'???in a while i should have said!

No.
If you enter 'Super' and enter
info.firstname[0]='S'
info.firstname[1]='u'
info.firstname[2]='p'
info.firstname[3]='e'
info.firstname[4]='r'
info.firstname[5]='\n'
info.firstname[6]=NULL
info.firstname[7] through [15] are undefined

So you'd want to use strlen to get the string length, and work backward checking for and writing null over whitespace characters to trim it.

Laika1986

Thanks again lads iv improved it a good bit, Im just about ready to start reading into the array now

#include <stdio.h>
#include <stdlib.h>
#define MAX 16



int main()
{

	FILE *fp, *fp2;
	fp2=fopen("employee.dat", "r");
	int j;
	


	typedef struct info{
		char first_name[MAX];
		char last_name[MAX];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		}info;

info id;
		int i;
//		for(i=0;i<100;i++){
		
		printf("\nPlease enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		printf("\nPlease enter First name: ");
		fgets(id.first_name,MAX,stdin);
		int count;//intializes count to zero
		for (count=0; count<MAX; count++){//loops while number is less than max
			if (id.first_name[count]== '\n'){//if the value is the new line char replaces it with null
				id.first_name[count]= '\0';
			}
		}
			
		printf("\nPlease enter Last name: ");
		fgets(id.last_name,MAX,stdin);
		printf("\nPlease enter hours worked: ");
		scanf("%d",&id.hours);
		printf("\nPlease enter rate of pay: ");
		scanf("%f",&id.rate);
		printf("\nPlease enter rate of tax: ");
		scanf("%f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		fp=fopen("employee.dat","w");
		
		
		fprintf(fp,"ID Number: %d,",id.identification);
		fprintf(fp,"First Name: %s,",id.first_name);
		fprintf(fp,"Last Name: %s, ",id.last_name);
		fprintf(fp,"Hours Worked: %d,",id.hours);
		fprintf(fp,"Rate of Pay: %.2f,",id.rate);
		fprintf(fp,"Rate of Tax: %.2f,",id.tax);
		fprintf(fp,"Gross Pay: %.2f,",id.gross);
		fprintf(fp,"Net Pay: %.2f,",id.net);
		
		fp2=fopen("employee.dat","r");		
		
//}		
		
return 0;
}

Cork24

Please dont Define Array Size

Good Programing should Allow the User to Define how many Records he may want to place inside it..

But for starting off it would be ok, but dont get into that type of Programing.

Plus why are you doing i <100 your Array is define to 16 ?

use...

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

Laika1986

Yeah i understand what you mean as regards allowing the user to define the amount of records they can enter, I would do this but i dont think ill have time!I have taken that for loop out of it for the time being until i get the basics working properly

Cork24

Try

#include <iostream>
#include<string>
#include<sstream>

#define N_Employee  16


using namespace std;


int x[N_Employee];

struct  employee
{


    int Employee_number;             
    string EmployeeFName;    
     string EmployeeLName;           
    int hours;
float rate;
              float tax;
float gross;
float net;  
};

employee record[N_Employee];


int main ()
{    
    
    int n;  
    
    for (n = 0; n < N_Employee; n++)
    {
           while((cout<<"Enter Employee Number: ")&&(!  (cin>>record[n].Employee_number)||record[n].Employee_number<0))
        {
            cout<<"Invalid Input! Please Enter Employee Number "<<endl;
            cin.clear();
            cin.ignore(1000,'\n'); 
        }
        
        cout << "Enter Employee First  Name: ";
        cin >> record[n].EmployeeFName;  

   cout << "Enter Employee Last  Name: ";
        cin >> record[n].EmployeeLName;  ;
        
  
        while((cout<<"Enter Hours Worked: ")&&(!(cin>>record[n].hours)||record[n].hours<0))
        {
            cout<<"Invalid Input! Please Enter Hours Worked"<<endl;
            cin.clear();
            cin.ignore(1000,'\n'); 
        }
        

        while((cout<<"Enter Rate: ")&&(!(cin>>record[n].rate)||record[n].rate<0))
        {
            cout<<"Invalid Input! Please Enter Rate"<<endl;
            cin.clear();
            cin.ignore(1000,'\n'); 
        }



        while((cout<<"Enter Tax: ")&&(!(cin>>record[n].tax)||record[n].tax<0))
         {
             cout<<"Invalid Input! Please Enter Tax"<<endl;
             cin.clear();
             cin.ignore(1000,'\n'); 
         }


        while((cout<<"Enter gross: ")&&(!(cin>>record[n].gross)||record[n].gross<0))
         {
             cout<<"Invalid Input! Please Enter Gross"<<endl;
             cin.clear();
             cin.ignore(1000,'\n'); 
         }




        while((cout<<"Enter Net: ")&&(!(cin>>record[n].net)||record[n].net<0))
         {
             cout<<"Invalid Input! Please Enter Net"<<endl;
             cin.clear();
             cin.ignore(1000,'\n'); 
         }

This should Loop Over 16 Times and then you can


Read in the Array

 for(int i=0; i<N_Employee; i++)
               {
                   cout << "Employee Number: " <<record[i].employee_number << endl;   
 

                   cout << " " << record[i]. << endl;         


etc....


               }

Laika1986

Thanks for the help but is that C++?? it's useful though

Cork24

You doing c# or c++

SirLemonhead

The code in his/her original post is C...

I think the people trying to help are just as confused as the OP is :pac:

Do you need to store this data in a .dat file as text, or can it be binary data? ie if someone opens it in Notepad, should they see human readable understandable text?

Edit: Sorry I see, it's a plain text file..

Cork24

Im sorry i was using my iphone,

But OP C & C++ are more or less the same, its just C++ had added Lib,

ressem

Cork24 wrote: »

Im sorry i was using my iphone,

But OP C & C++ are more or less the same, its just C++ had added Lib,

Sorry Cork, that's not accurate and since Laika's in learning mode I'm going to be pedantic. Most of c is a subset of c++, and most of us can use a c++ compiler to compile our c code for x86 without hassle.
But a dedicated c compiler will not process c++ even if the libraries are available. C has no call-by-reference for example.

The OP has been given a C project, then s/he can't even count on the Gnu C getline() function mentioned by Kidchameleon as a good alternative to scanf / fgets (or all the other non-standard alternatives like scanf_s).
A PITA when we're starting to learn C, and every tutorial says not to use this and that unsafe functions in real code due to buffer overflow concerns.

Laika1986

Well guys to clear up some confusion yes indeed I am doing C.

@Cork24 I do appreciate that code although its in C++ like i said I can see the logic in it to a certain extent.

@Everyone! Thanks for your help and suggestions, I can only guess how frustrating it is to deal with noobs like myself but we all know it's no-ones fault really!

Laika1986

Hey Guys. New problem, at the lower section of my code i have a type fo search function so when the user enters a number it prints the relevant details for that ID number. If the number does not exist it produces and error. However the array seems to be empty. I had this working earlier but now im at a loss to what i changed that breaks it, any help as always would be great

#include <stdio.h>
#include <stdlib.h>
#define MAX 16



int main()
{

	FILE *fp, *fp2;
	
	fp=fopen("employee.dat","a");
	
	


	typedef struct info{
		char first_name[MAX];
		char last_name[MAX];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		}info;

info id;
info array[100];
		
		
		
		
		

		
		printf("\nPlease enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		
			if (id.identification==array[100].identification){
		
					printf("Error: User already exists");
					
				}
			
		printf("\nPlease enter First name: ");
		fgets(id.first_name,MAX,stdin);
		
		int count;//intializes count to zero
		for (count=0; count<MAX; count++){//loops while number is less than max
			if (id.first_name[count]== '\n'){//if the value is the new line char replaces it with null
				id.first_name[count]= '\0';
			}
		}
			
		printf("\nPlease enter Last name: ");
		fgets(id.last_name,MAX,stdin);
		
		for (count=0; count<MAX; count++){//loops while number is less than max
			if (id.last_name[count]== '\n'){//if the value is the new line char replaces it with null
				id.last_name[count]= '\0';
			}
		}
		
		printf("\nPlease enter hours worked: ");
		scanf("%d",&id.hours);
		printf("\nPlease enter rate of pay: ");
		scanf("%f",&id.rate);
		printf("\nPlease enter rate of tax: ");
		scanf("%f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		
		
		fprintf(fp,"ID Number: %d,",id.identification);
		fprintf(fp,"First Name: %s,",id.first_name);
		fprintf(fp,"Last Name: %s, ",id.last_name);
		fprintf(fp,"Hours Worked: %d,",id.hours);
		fprintf(fp,"Rate of Pay: %.2f,",id.rate);
		fprintf(fp,"Rate of Tax: %.2f,",id.tax);
		fprintf(fp,"Gross Pay: %.2f,",id.gross);
		fprintf(fp,"Net Pay: %.2f,\n",id.net);
		
		
	
		int idnum,i;	
		printf("Please enter ID Number: ");
		scanf("%d",&idnum);
		
		for(i=0;i<=100;i++){
		
			if (idnum==array[i].identification){
				
				printf("%s ",id.first_name);
				printf("%s\n",id.last_name);
				printf("Hours: %d\n",id.hours);
				printf("Pay: %.2f\n",id.rate);
				printf("Tax: %.2f\n",id.tax);
				printf("Gross Pay: %.2f\n",id.gross);
				printf("Net Pay: %.2f\n",id.net);
				}
				
			else if(idnum!=array[i].identification){
				printf("Error: User does not exist");
				break;
				}
			}
				
				
		
		
	
		
return 0;
}

ressem

Course not.
At no point do you put anything into the array.

What tools are you using to write and debug the code? Most will support watching variables and arrays as they change when you step through the code in debug mode one line at a time.
Then it's much quicker to find what you're missing, and when your code does not behave as you're expecting.

You'll have to learn this, perhaps from a TA, a student colleague, your notes, the help file of the program or a youtube video.

Laika1986 wrote: »

Hey Guys. New problem, at the lower section of my code i have a type fo search function so when the user enters a number it prints the relevant details for that ID number. If the number does not exist it produces and error. However the array seems to be empty. I had this working earlier but now im at a loss to what i changed that breaks it, any help as always would be great

#include <stdio.h>
#include <stdlib.h>
#define MAX 16



int main()
{

	FILE *fp, *fp2;
	
	fp=fopen("employee.dat","a");
	
	


	typedef struct info{
		char first_name[MAX];
		char last_name[MAX];
		int identification;
		int hours;
		float rate;
		float tax;
		float gross;
		float net;
		}info;

info id;
info array[100];
		
		
		
		
		

		
		printf("\nPlease enter ID Number: ");
		scanf("%d",&id.identification);
		fflush(stdin);
		
			if (id.identification==array[100].identification){
		
					printf("Error: User already exists");
					
				}
			
		printf("\nPlease enter First name: ");
		fgets(id.first_name,MAX,stdin);
		
		int count;//intializes count to zero
		for (count=0; count<MAX; count++){//loops while number is less than max
			if (id.first_name[count]== '\n'){//if the value is the new line char replaces it with null
				id.first_name[count]= '\0';
			}
		}
			
		printf("\nPlease enter Last name: ");
		fgets(id.last_name,MAX,stdin);
		
		for (count=0; count<MAX; count++){//loops while number is less than max
			if (id.last_name[count]== '\n'){//if the value is the new line char replaces it with null
				id.last_name[count]= '\0';
			}
		}
		
		printf("\nPlease enter hours worked: ");
		scanf("%d",&id.hours);
		printf("\nPlease enter rate of pay: ");
		scanf("%f",&id.rate);
		printf("\nPlease enter rate of tax: ");
		scanf("%f",&id.tax);
		id.gross= id.hours*id.rate;
		id.net=id.gross-(id.gross*id.tax/100);
		
		
		
		
		fprintf(fp,"ID Number: %d,",id.identification);
		fprintf(fp,"First Name: %s,",id.first_name);
		fprintf(fp,"Last Name: %s, ",id.last_name);
		fprintf(fp,"Hours Worked: %d,",id.hours);
		fprintf(fp,"Rate of Pay: %.2f,",id.rate);
		fprintf(fp,"Rate of Tax: %.2f,",id.tax);
		fprintf(fp,"Gross Pay: %.2f,",id.gross);
		fprintf(fp,"Net Pay: %.2f,\n",id.net);
		
		
	
		int idnum,i;	
		printf("Please enter ID Number: ");
		scanf("%d",&idnum);
		
		for(i=0;i<=100;i++){
		
			if (idnum==array[i].identification){
				
				printf("%s ",id.first_name);
				printf("%s\n",id.last_name);
				printf("Hours: %d\n",id.hours);
				printf("Pay: %.2f\n",id.rate);
				printf("Tax: %.2f\n",id.tax);
				printf("Gross Pay: %.2f\n",id.gross);
				printf("Net Pay: %.2f\n",id.net);
				}
				
			else if(idnum!=array[i].identification){
				printf("Error: User does not exist");
				break;
				}
			}
				
				
		
		
	
		
return 0;
}