Thread: reading a file

I want it to print if the user says they want to see they list. I need to give them the option to see the list or just add data. and i want the list to print to the screen if i use fprintf that print to the file which is not wnat i want to do.

i did something wrong. i think that my while statement should be changed. because there is no data to read. any help. is htere any way to put a third option in to termanit the second time around an start like a do loop till number 3 but only after it gives the user option 1 and option 2 but i need to know how to get inside of my loop i think i need a fscanf to read the data before it goes into the while statment.

Code:

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


#define FLASE 0
#define TRUE 1
#define Nlen 25

typedef struct person{
     char FName [Nlen +1];
     char LName [Nlen +1];
     char Sex;
     char Grade;
     struct person *Next;
} PERSON;

void PrintList (PERSON*);
int DeletePerson;
PERSON* InsertNode (PERSON*, PERSON*);     

main ()
{
    PERSON *STU; //TEmp pointer used to creat list
    int Ans;    //User responce
    int Len,      //Name Length
        Deleted; //True if requested item deleted
    char FName [Nlen +1];  // first name
    char LName [Nlen +1];  // lase name
    char Grade, Sex, Ans1; 
    FILE *fin;
     fin = fopen( "e:data.dat", "rw");
     
PERSON *TOP = NULL; //Initialize top list point to Null     
    
     
 while (fscanf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, STU->Sex,STU->Grade) != EOF){
     
      printf ("chose option you want to do\n");
      printf ("Option 1 : Enter New Recode");
      printf ("Option 2 : Display List");
      scanf ("%d", Ans);
      
       switch (Ans){
          case '1' :       
             STU = (PERSON*) malloc (sizeof (PERSON));
              if (STU == NULL)
                printf ("Error -- could not allocate memory\n\n");
              else {
                 printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->FName, Nlen+1, stdin);
                 Len = strlen (STU->FName);
                   if (STU->FName[Len-1]== '\n')
                       STU->FName [Len-1] == '\0';
                  
                  printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->LName, Nlen+1, stdin);
                 Len = strlen (STU->LName);
                   if (STU->LName[Len-1]== '\n')
                       STU->LName [Len-1] = '\0';  
                   
                 printf ("Please enter Sex");
                 scanf ("%c", &STU->Sex);
                 printf ("Please enter Grade");
                 scanf ("%c", &STU->Grade);  
                 STU->Next= NULL; 
                  break;         
                 } //else statment end
                         
             
            case '2' :
                 fscanf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, STU->Sex,STU->Grade);
                 printf ("%s %s %c %c\n", LName, FName, Sex, Grade);
                  break;        
                  
                  }
                  }
 getchar ();
 getchar ();
 return 0;
}

Code:

while (fscanf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, &STU->Sex,&STU->Grade) != EOF){

Nlen, should not be there at all. You are trying to store a value in '25'

You have more problems in your code with not passing an address to scanf, pay attention to your warnings

Ans is an int, your switch conditions should be ints
case 1: NOT case '1':

The flow of you program does not make any sense.
For each time you read a line from the file you want run all of your program logic?

You'll probably want to break things into functions, some quick pseudo code for thought...

Code:

while(menu_choice != quit) {
  print menu();
  get_choice();
  switch(menu_choice) {
    1: new_student;
    2: print_students;
    3: quit
    default: error try again
  }
}

new_student {
  open_file in append mode
  get info from user
  write to file
  close file
}

print_students {
  open file in read mode
  print file to screen
  close file
}

You could read your file into a data structure instead of opening and closing the file for each read/write, but this would be a good firstcut.
If you read all the data into an array or linked list you can work with that and only have to open the file once for reading (when your program starts) and once to write the data back out when you quit.

ok i will try it that way and show you what i have. just let me know if in going in the correct direction with it please. is this what you are talking about. I"m still working on it im getting this error the lines are highlieted in blue. SO what am i doing wrong.

56 E:\tmitchellwk8a.cpp expected `;' before '{' token
80 E:\tmitchellwk8a.cpp expected `;' before '{' token

Code:

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


#define FLASE 0
#define TRUE 1
#define Nlen 25

typedef struct person{
     char FName [Nlen +1];
     char LName [Nlen +1];
     char Sex;
     char Grade;
     struct person *Next;
} PERSON;

void PrintList (PERSON*);
int DeletePerson;
int new_student;
int print_students;

PERSON* InsertNode (PERSON*, PERSON*);     

main ()
{
    PERSON *STU; //TEmp pointer used to creat list
    int Ans, menu_choice, quit;    //User responce
    int Len,      //Name Length
        Deleted; //True if requested item deleted
    char FName [Nlen +1];  // first name
    char LName [Nlen +1];  // lase name
    char Grade, Sex, Ans1; 
    FILE *fin, *fout;
     
   
     
 while(menu_choice != quit) 
 {
  printf ("chose option you want to do\n");
      printf ("Option 1 : Enter New Recode");
      printf ("Option 2 : Display List");
  scanf ("%d", menu_choice);
  switch(menu_choice) {
    case '1': 
         new_student;
    case '2':
          print_students;
    case '3':
          quit;
    case '': 
     printf ("error try again");
     }
}

 new_student {
  fin = fopen( "e:data.dat", "r");//open_file in append mode
   // get info from user
  printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->FName, Nlen+1, stdin);
                 Len = strlen (STU->FName);
                   if (STU->FName[Len-1]== '\n')
                       STU->FName [Len-1] == '\0';
                  
                  printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->LName, Nlen+1, stdin);
                 Len = strlen (STU->LName);
                   if (STU->LName[Len-1]== '\n')
                       STU->LName [Len-1] = '\0';  
                   
                 printf ("Please enter Sex");
                 scanf ("%c", &STU->Sex);
                 printf ("Please enter Grade");
                 scanf ("%c", &STU->Grade);  
                 STU->Next= NULL;
   fprintf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, STU->Sex,STU->Grade);
  fout = fclose( "e:data.dat");//close file
}

 print_students {
 fin = fopen( "e:data.dat", "r"); //open file in read mode
   fscanf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, &STU->Sex,&STU->Grade);
                 printf ("%s %s %c %c\n", LName, FName, Sex, Grade); //print file to screen
    fout = fclose( "e:data.dat"); // close file
}
 getchar ();
 getchar ();
 return 0;
}

//sort array

Code:

while (fscanf(fin, "%25[^ ]. %25[^ ].%c %c\n", Nlen, STU->LName, STU->FName, STU->Sex,STU->Grade) != EOF){

Are there really periods [nod to those elsewhere: full stops] in the text?
And don't compare for one possible failure before assuming you got what you wanted, check for success -- that is, did you successfully scan the 5 items?
And why not use fgets/sscanf?
And since it's whitespace, I guess I could have used %25s instead of %25[^ ]. (The period at is at the end of the sentence to mark the end of the sentence, not part of the format specifier.)

I'm able to get it into the while statment and it shows the options. But i keep gettign a referance window in dos when i hit one of the options what did i do wrong.

Code:

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


#define FLASE 0
#define TRUE 1
#define Nlen 25

typedef struct person{
     char FName [Nlen +1];
     char LName [Nlen +1];
     char Sex;
     char Grade;
     struct person *Next;
} PERSON;

void PrintList (PERSON*);
int DeletePerson;
PERSON* InsertNode (PERSON*, PERSON*);     

main ()
{
    PERSON *STU; //TEmp pointer used to creat list
    int Ans;    //User responce
    int Len,      //Name Length
        Deleted; //True if requested item deleted
    char FName [Nlen +1];  // first name
    char LName [Nlen +1];  // lase name
    char Grade, Sex, Ans1; 
    FILE *fin;
    
     
PERSON *TOP = NULL; //Initialize top list point to Null     
 fin = fopen( "e:data.txt", "rw");    
     
 while (fscanf(fin, "%25s %25s %c %c\n", Nlen, STU->LName, STU->FName, STU->Sex,STU->Grade) == EOF){
 {
      
      printf ("chose option you want to do\n");
      printf ("Option 1 : Enter New Recode\n");
      printf ("Option 2 : Display List\n");
      printf ("Option 3 : Quit\n");
      scanf ("%d", Ans);
      
       switch(Ans){
          case '1' :       
            STU = (PERSON*) malloc (sizeof (PERSON));
             if (STU == NULL)
                printf ("Error -- could not allocate memory\n\n");
             else {
                 printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->FName, Nlen+1, stdin);
                 Len = strlen (STU->FName);
                   if (STU->FName[Len-1]== '\n')
                       STU->FName [Len-1] == '\0';
                  
                  printf ("\nEnter students first name ( uo to %d letters):", Nlen);
                 fgets (STU->LName, Nlen+1, stdin);
                 Len = strlen (STU->LName);
                   if (STU->LName[Len-1]== '\n')
                       STU->LName [Len-1] = '\0';  
                   
                 printf ("Please enter Sex");
                 scanf ("%c", &STU->Sex);
                 printf ("Please enter Grade");
                 scanf ("%c", &STU->Grade);  
                 STU->Next= NULL; 
                  break;         
                } //else statment end
                         
             
            case '2' :
                 fscanf(fin, "%25s %25s %c %c\n", Nlen, STU->LName, STU->FName, &STU->Sex, &STU->Grade);
                 printf ("%s %s %c %c\n", LName, FName, Sex, Grade);
                 break; 
                        
              case '3' :  
                  printf ("you chose to exit.  Hit enter to close");  
                  break; 
            }//end of switch
      } // end of while
      }
 getchar ();
 getchar ();
 return 0;
}

i was trying to do it. but i think that im taking the long way around. i put in a linked list. But i have not sorted it or even tried to see if it works. here is what i have.

but i think you are showing me a better way to do that i can understand.

Code:

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

#define Nlen    26

typedef struct person_t {
   char FName[Nlen];
   char LName[Nlen];
   char Sex;
   char Grade;
   struct person_t *next;
} PERSON;

void amend_file( char file[], PERSON *STU );
void show_file( char file[], PERSON *STU );
void insert( struct listNode   *newnode,  /* new node */
				struct listNode   **start, /* first node */
				struct listNode   **last /* last node */
				)
{
	struct listNode  *oldptr, *ptr;
	if(*last == NULL) /* first node in linklist */
	{
             for (LName = )
             {
		newnode->nextPtr = NULL;
		newnode->priorPtr = NULL;
		*last = newnode;
		*start = newnode;
		return;
    }
	}
	ptr = *start; /* start at top of linklist */
	oldptr = NULL;

	while(ptr)
	{
		if(ptr->data < newnode->data )
		{
			oldptr = ptr;
			ptr = ptr->nextPtr;
		}
		else
		{
			if(ptr->priorPtr)
			{
				ptr->priorPtr->nextPtr = newnode;
				newnode->nextPtr = ptr;
				newnode->priorPtr = ptr->priorPtr;
				ptr->priorPtr = newnode;
				return;
			}
			newnode->nextPtr = ptr; /* newnode first node */
			newnode->priorPtr = NULL;
			ptr->priorPtr = newnode;
			*start = newnode;
			return;
		}
	}
	oldptr->nextPtr = newnode;
	newnode->nextPtr = NULL;
	newnode->priorPtr = oldptr;
	*last = newnode;
}
int main (void)
{
   PERSON *STU;
   int Ans;
   	struct listNode  *start = NULL;         
	struct listNode  *last = NULL;    
	struct listNode  *data = NULL;
	struct listNode  *tempnode  = NULL;  
   char file[] = "e:data.txt";

   do
   {
      printf("1. Enter new record\n"
             "2. Display List\n"
             "3. Quit\n\n");
      printf("Prompt: ");
      fflush(stdout);
      if ( scanf("%d", &Ans) == 1 ) /* get answer */
      {
         STU = (PERSON*) malloc (sizeof (PERSON));
         if (STU == NULL)
         {
            perror("PERSON");
            exit(EXIT_FAILURE);
         }
         switch(Ans)
         {
            case 1:
               amend_file(file, STU);
               break;
            case 2:
               show_file(file, STU);
               break;
            case 3: default:
               Ans = 3;
               break;
         }
      } 
    for (LName = ){  data = (struct listNode  *) malloc(sizeof(listNode));
		if(!data)
			return -1;
		data->data=  Stu->LName ;
		insert(data, &start, &last);/}
* /get answer */
   }
   while ( Ans != 3 );
   free(STU);
   return EXIT_SUCCESS;
}
/*
 * amend_file: Enter stuff into the working file.
 * Very much a bare bones function so far; work on making this better
 * Perhaps make it work with a linked list, as your struct suggests?
 */
void amend_file( char file[], PERSON *HEAD )
{
   assert(HEAD != NULL);
   FILE *fin = fopen(file, "a");
   if ( fin == NULL )
   {
      perror(file);
      exit(EXIT_FAILURE);
   }
   printf("Enter new record (EOF to quit): ");
   while (
    scanf("%s %s %c %c", HEAD->FName, HEAD->LName, &HEAD->Sex,
      &HEAD->Grade) == 4
   )
   {
     fprintf(fin, "%s %s %c %c\n", HEAD->FName, HEAD->LName, HEAD->Sex,
        HEAD->Grade);
     fflush(fin);
   }
   fclose(fin);
}
/*
 * show_file: Reads the working file.
 * Bare bones again...
 */
void show_file ( char file[], PERSON *HEAD )
{
  assert(HEAD != NULL);
  int i = 1;
  FILE *fout = fopen(file, "r");
  if (file == NULL)
  {
    perror(file);
    exit(EXIT_FAILURE);
  }
  while (
   fscanf(fout, "%s %s %c %c", HEAD->FName, HEAD->LName, &HEAD->Sex,
     &HEAD->Grade) == 4
  )
  {
    printf("Record %d: %s %s %c %c\n", i, HEAD->FName, HEAD->LName,
       HEAD->Sex, HEAD->Grade);
    i++;
  }
  fclose(fout);
}

Code:

fflush(fin);

Reason?

There are perhaps still a few issues:

main.c:20: warning: "struct listNode" declared inside parameter list
main.c:20: warning: its scope is only this definition or declaration, which is probably not what you want
main.c: In function `insert':
main.c:25: error: `LName' undeclared (first use in this function)
main.c:25: error: (Each undeclared identifier is reported only once
main.c:25: error: for each function it appears in.)
main.c:25: error: syntax error before ')' token
main.c:28: error: dereferencing pointer to incomplete type
main.c: At top level:
main.c:34: error: `start' undeclared here (not in a function)
main.c:34: warning: data definition has no type or storage class
main.c:35: warning: initialization makes integer from pointer without a cast
main.c:35: warning: data definition has no type or storage class
main.c:37: error: syntax error before "while"
main.c:42: error: redefinition of 'ptr'
main.c:34: error: previous definition of 'ptr' was here
main.c:42: error: invalid type argument of `->'
main.c:42: warning: data definition has no type or storage class
main.c:43: error: syntax error before '}' token
main.c:57: error: `newnode' undeclared here (not in a function)
main.c:57: warning: data definition has no type or storage class
main.c:58: error: syntax error before "return"
main.c:64: warning: data definition has no type or storage class
main.c:65: error: syntax error before '}' token
main.c: In function `main':
main.c:104: error: `LName' undeclared (first use in this function)
main.c:104: error: syntax error before ')' token
main.c:107: error: dereferencing pointer to incomplete type
main.c:107: error: `Stu' undeclared (first use in this function)
main.c:108: warning: passing arg 1 of `insert' from incompatible pointer type
main.c:108: warning: passing arg 2 of `insert' from incompatible pointer type
main.c:108: warning: passing arg 3 of `insert' from incompatible pointer type
main.c:108: error: syntax error before '/' token
main.c: At top level:
main.c:112: warning: parameter names (without types) in function declaration
main.c:112: error: conflicting types for 'free'
C:/Progra~1/CodeBlocks/bin/../lib/gcc/mingw32/3.4.4/../../../../include/stdlib.h:348: error: previous declaration of 'free' was here
main.c:112: error: conflicting types for 'free'
C:/Progra~1/CodeBlocks/bin/../lib/gcc/mingw32/3.4.4/../../../../include/stdlib.h:348: error: previous declaration of 'free' was here
main.c:112: warning: data definition has no type or storage class
main.c:113: error: syntax error before "return"

would you like me to post my linked list and sort alagrithem them and the work on puting the two together.

the other problem that i have is that 1 i can get out of the loop. I should be able to enter in one data and the be prompted at the list again. How do I do that. here is what i came up for my linked list. just courise how do i pass the rest of the strct so that it all prints together. So I should do the sort first then pass it to the linked list or the other way aroound

Code:

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

struct listNode
{
	int data;
	struct listNode *priorPtr;
	struct listNode *nextPtr;

}ListNode;

struct listNode  *start = NULL;         
struct listNode  *last = NULL;           

void insert( struct listNode   *newnode,  /* new node */
				struct listNode   **start, /* first node */
				struct listNode   **last /* last node */
				)
{
	struct listNode  *oldptr, *ptr;
	if(*last == NULL) /* first node in linklist */
	{
		newnode->nextPtr = NULL;
		newnode->priorPtr = NULL;
		*last = newnode;
		*start = newnode;
		return;
	}
	ptr = *start; /* start at top of linklist */
	oldptr = NULL;
	while(ptr)
	{
		if(ptr->data < newnode->data )
		{
			oldptr = ptr;
			ptr = ptr->nextPtr;
		}
		else
		{
			if(ptr->priorPtr)
			{
				ptr->priorPtr->nextPtr = newnode;
				newnode->nextPtr = ptr;
				newnode->priorPtr = ptr->priorPtr;
				ptr->priorPtr = newnode;
				return;
			}
			newnode->nextPtr = ptr; /* newnode first node */
			newnode->priorPtr = NULL;
			ptr->priorPtr = newnode;
			*start = newnode;
			return;
		}
	}
	oldptr->nextPtr = newnode;
	newnode->nextPtr = NULL;
	newnode->priorPtr = oldptr;
	*last = newnode;
}

int main(void)
{
	char LName;
	struct listNode  *start = NULL;         
	struct listNode  *last = NULL;    
	struct listNode  *data = NULL;
	struct listNode  *tempnode  = NULL;   
	srand( (unsigned)time( NULL ) );
	for(LName = a; LName< z;x++)
	{
		data = (struct listNode  *) malloc(sizeof(listNode));
		if(!data)
			return -1;
		data->data=  LName() ;
		insert(data, &start, &last);
	}
	tempnode = start;
	printf("From beginning to end\n");
	while(tempnode) // print out the list  from beginning to end
	{
		printf("data = %d\n",tempnode->data);
		tempnode = tempnode->nextPtr; 
	}
	tempnode = last;
	printf("\n\nFrom end to beginning\n");
	while(tempnode) // print out the list  from end to beginning
	{
		printf("data = %d\n",tempnode->data);
		tempnode = tempnode->priorPtr; 
	}
	return 0;
}