/*
This program reads a random access file sequentially, updates data
already written to the file, creates new data to be placed in the
file, and deletes data previously in the file. */
#include <stdio.h>
/* clientData structure definition */
struct clientData {
int acctNum; /* account number */
char lastName[15]; /* account last name */
char firstName[10]; /* account first name */
double balance; /* account balance */
}; /* end structure clientData */
/* prototypes */
int enterChoice( void );
void textFile( FILE *readPtr );
void updateRecord( FILE *fPtr );
void newRecord( FILE *fPtr );
void deleteRecord( FILE *fPtr );
int main( void )
{
FILE *cfPtr; /* credit.dat file pointer */
int choice; /* user's choice */
/* fopen opens the file; exits if file cannot be opened */
if ( ( cfPtr = fopen( "credit.dat", "rb+" ) ) == NULL ) {
printf( "File could not be opened.\n" );
} /* end if */
else {
/* enable user to specify action */
while ( ( choice = enterChoice() ) != 5 ) {
switch ( choice ) {
/* create text file from record file */
case 1:
textFile( cfPtr );
break;
/* update record */
case 2:
updateRecord( cfPtr );
break;
/* create record */
case 3:
newRecord( cfPtr );
break;
/* delete existing record */
case 4:
deleteRecord( cfPtr );
break;
/* display message if user does not select valid choice */
default:
printf( "Incorrect choice\n" );
break;
} /* end switch */
} /* end while */
fclose( cfPtr ); /* fclose closes the file */
} /* end else */
return 0; /* indicates successful termination */
} /* end main */
/* create formatted text file for printing */
void textFile( FILE *readPtr )
{
FILE *writePtr; /* accounts.txt file pointer */
/* create clientData with default information */
struct clientData client = { 0, "", "", 0.0 };
/* fopen opens the file; exits if file cannot be opened */
if ( ( writePtr = fopen( "accounts.txt", "w" ) ) == NULL ) {
printf( "File could not be opened.\n" );
} /* end if */
else {
rewind( readPtr ); /* sets pointer to beginning of file */
fprintf( writePtr, "%-6s%-16s%-11s%10s\n",
"Acct", "Last Name", "First Name","Balance" );
/* copy all records from random-access file into text file */
while ( !feof( readPtr ) ) {
fread( &client, sizeof( struct clientData ), 1, readPtr );
/* write single record to text file */
if ( client.acctNum != 0 ) {
fprintf( writePtr, "%-6d%-16s%-11s%10.2f\n",
client.acctNum, client.lastName,
client.firstName, client.balance );
} /* end if */
} /* end while */
fclose( writePtr ); /* fclose closes the file */
} /* end else */
} /* end function textFile */
/* update balance in record */
void updateRecord( FILE *fPtr )
{
int account; /* account number */
double transaction; /* transaction amount */
/* create clientData with no information */
struct clientData client = { 0, "", "", 0.0 };
/* obtain number of account to update */
printf( "Enter account to update ( 1 - 100 ): " );
scanf( "%d", &account );
/* move file pointer to correct record in file */
fseek( fPtr, ( account - 1 ) * sizeof( struct clientData ), SEEK_SET );
/* read record from file */
fread( &client, sizeof( struct clientData ), 1, fPtr );
/* display error if account does not exist */
if ( client.acctNum == 0 ) {
printf( "Acount #%d has no information.\n", account );
} /* end if */
else { /* update record */
printf( "%-6d%-16s%-11s%10.2f\n\n", client.acctNum, client.lastName, client.firstName, client.balance );
/* request transaction amount from user */
printf( "Enter charge ( + ) or payment ( - ): " );
scanf( "%lf", &transaction );
client.balance += transaction; /* update record balance */
printf( "%-6d%-16s%-11s%10.2f\n", client.acctNum, client.lastName, client.firstName, client.balance );
/* move file pointer to correct record in file */
fseek( fPtr, ( account - 1 ) * sizeof( struct clientData ), SEEK_SET );
/* write updated record over old record in file */
fwrite( &client, sizeof( struct clientData ), 1, fPtr );
} /* end else */
} /* end function updateRecord */
/* delete an existing record */
void deleteRecord( FILE *fPtr )
{
struct clientData client; /* stores record read from file */
struct clientData blankClient = { 0, "", "", 0 }; /* blank client */
int accountNum; /* account number */
/* obtain number of account to delete */
printf( "Enter account number to delete ( 1 - 100 ): " );
scanf( "%d", &accountNum );
/* move file pointer to correct record in file */
fseek( fPtr, ( accountNum - 1 ) * sizeof( struct clientData ), SEEK_SET );
/* read record from file */
fread( &client, sizeof( struct clientData ), 1, fPtr );
/* display error if record does not exist */
if ( client.acctNum == 0 ) {
printf( "Account %d does not exist.\n", accountNum );
} /* end if */
else { /* delete record */
/* move file pointer to correct record in file */
fseek( fPtr, ( accountNum - 1 ) * sizeof( struct clientData ), SEEK_SET );
/* replace existing record with blank record */
fwrite( &blankClient, sizeof( struct clientData ), 1, fPtr );
} /* end else */
} /* end function deleteRecord */
/* create and insert record */
void newRecord( FILE *fPtr )
{
/* create clientData with default information */
struct clientData client = { 0, "", "", 0.0 };
int accountNum; /* account number */
/* obtain number of account to create */
printf( "Enter new account number ( 1 - 100 ): " );
scanf( "%d", &accountNum );
/* move file pointer to correct record in file */
fseek( fPtr, ( accountNum - 1 ) * sizeof( struct clientData ), SEEK_SET );
/* read record from file */
fread( &client, sizeof( struct clientData ), 1, fPtr );
/* display error if account already exists */
if ( client.acctNum != 0 ) {
printf( "Account #%d already contains information.\n",
client.acctNum );
} /* end if */
else { /* create record */
/* user enters last name, first name and balance */
printf( "Enter lastname, firstname, balance\n? " );
scanf( "%s%s%lf", &client.lastName, &client.firstName, &client.balance );
client.acctNum = accountNum;
/* move file pointer to correct record in file */
fseek( fPtr, ( client.acctNum - 1 ) * sizeof(struct clientData ), SEEK_SET );
/* insert record in file */
fwrite( &client, sizeof( struct clientData ), 1, fPtr );
} /* end else */
} /* end function newRecord */
/* enable user to input menu choice */
int enterChoice( void )
{
int menuChoice; /* variable to store user's choice */
/* display available options */
printf( "\nEnter your choice\n"
"1 - store a formatted text file of acounts called\n"
" \"accounts.txt\" for printing\n"
"2 - update an account\n"
"3 - add a new account\n"
"4 - delete an account\n"
"5 - end program\n? " );
scanf( "%d", &menuChoice ); /* receive choice from user */
return menuChoice;
} /* end function enterChoice */
