Problems with running a Program with files - c

Question

I have a school project and that project is making a C programming dictionary which will contain basic C statements and their meanings and uses. These statements and meanings will be inputted by me. Whatever I input will be stored in the file Dictionary.dat.
#include<stdio.h>
#include<conio.h>
#include<string.h>
typedef struct
{
char word[30], meaning[1000];
}lib;
void intro(void);
void updateword(FILE*,lib);
void addword(FILE*,lib);
void showMeaning(FILE*,lib);
void letter(FILE*,lib);
void showAll(FILE*,lib);
int main()
{
char pass[8], choice;
lib a;
FILE *f=fopen("Dictionary.dat","a+b");
printf("Enter Admin code: ");
gets(pass);
if(strcmp(pass,"turla")==0)
{
printf("Welcome to Admin page\n");
printf("What will do?\n(U)-update\t(A)-Add Word\n(S)-Show All\t");
printf("(L)-Show by Letter\n(M)-Show Meaning\n");
while(choice!='E'||choice!='e')
{
scanf("%c",&choice);
if(f!=NULL)
{
switch(choice)
{
case 'U': updateword(f,a);break;
case 'A': addword(f,a);break;
case 'S': showAll(f,a);break;
case 'L': letter(f,a);break;
case 'M': showMeaning(f,a);break;
case 'E': printf("closing");break;
}
}
}}
else
{
printf("W e l c o m e t o C P r o g r a m m i n g D i c t i o n a r y !\n");
printf("\t A Dictionary for C programming terms\n\n");
printf("What would you want to do? do?\n\n (S)-Search terms\t(L)-Search by letter\n(A)-Show All\n");
scanf("%c",&choice);
while(choice!='E'||choice!='e')
{
intro();
switch(choice)
{
case 'A':
case 'a': showAll(f,a); break;
case 'L':
case 'l': letter(f,a); break;
case 'S':
case 's': showMeaning(f,a); break;
case 'E':
case 'e': printf("closing..."); break;
}
}
system("cls");
}
fclose(f);
getch();
return 0;
}
void intro(void)
{
printf("W e l c o m e t o C P r o g r a m m i n g D i c t i o n a r y !\n");
printf("\t A Dictionary for C programming terms\n\n");
printf("What would you want to do? do?\n\n (S)-Search terms\t(L)-Search by letter\n(A)-Show All\n");
}
void updateword(FILE*ptr,lib a)
{
char srchWrd[30],choice,qtn='Y';
printf("Enter Word to update: ");
gets(srchWrd);
while(fread(&a,sizeof(lib),1,ptr))
{
system("cls");
if(strcmp(srchWrd,a.word)==0)
{
printf("What will you change? (W)-Word (M)-Meaning");
scanf("%c",&choice);
while(qtn!='N'||qtn!='n')
{
switch(choice)
{
case 'W':
case 'w': gets(a.word); printf("Do you still want to edit?(Y/N): "); scanf("%c",&qtn); break;
case 'M':
case 'm': gets(a.meaning); printf("Do you still want to edit?(Y/N): "); scanf("%c",&qtn); break;
default: printf("Invalid option. Enter Again");
}
}
fseek(ptr,sizeof(lib)*-1,1);
fwrite(&a,sizeof(lib),1,ptr);
}}
}
void addword(FILE*ptr,lib a)
{
printf("Enter word: ");fflush(stdin);
gets(a.word);
printf("Enter Meaning: ");fflush(stdin);
gets(a.meaning);
fwrite(&a,sizeof(lib),1,ptr);
}
void showMeaning(FILE*ptr,lib a)
{
char wrd[30];
int ctr=0;
printf("Search: ");
gets(wrd);
while(fread(&a,sizeof(lib),1,ptr))
{
if(strcmp(wrd,a.word)==0)
{
printf("\t%s",a.meaning);
ctr ++;
}
}
if(ctr==0)
printf("No word or symbol found in Dictionary");
}
void letter(FILE*ptr,lib a)
{
char ltr;
int ctr;
printf("Enter Letter");
scanf("%c",&ltr);
while(fread(&a,sizeof(lib),1,ptr))
{
if(ltr==a.word[0])
{
printf("%s - %s",a.word,a.meaning);
ctr++;
}
}
if(ctr==0)
printf("No search results");
}
void showAll(FILE*ptr,lib a)
{
while(fread(&a,sizeof(lib),1,ptr))
printf("%s - %s",a.word,a.meaning);
}
I have problems inputting the first word because It will always ask me to enter a word even if the else statement terminates. I am using C language, not C++.

Answer 1

I got your problem. You problem is at this line.
while(choice!='E'||choice!='e')
You're using OR operation instead of AND operation. So, that line should be
while((choice != 'E') && (choise != 'e')).
Why your code failed when entering e or E:
If you entered e then,
while( `e` != `E` || `e` != `e`)
----------
^
returns true. so controller goes to the while loop.
same with E too.
How && works:
If you entered e then,
while( `e` != `E` && `e` != `e`)
----------
^
returns true and checks second condition
while( `e` != `E` || `e` != `e`)
---------- ---------
^ ^
returns true. returns false. Condition failed. Don't enter into while.
Edit: 2nd problem
In else block, in switch-case add this instruction:
scanf("%c",&choice);
ohterwise your loop executes continuously.

Answer 2

There seem to be verious issues with your program. I'll address the mixed scanf and gets input I've hinted at in my comment here.
When you want to add an entry, you type 'A'. Nothing happens. That's because the input is buffered and is not sent to the program until a new-line was received, i.e. until the user presses return. Which the user does, of course, because nothing happend when 'A' was pressed. The 'A' still sits in the buffer, however. Now you ask the user to provide a word, which is read from the bufer with gets, which reads input until the end of a line is found.
But yout input bufer looks like this:
A newline w o r d newline
The 'A' has been consumed by scanf, but the newline hasn't. The next line you read is an empty line.
I suggest that you write a little framework for your most typical cases: Picking an item from a menu by typing a single letter plus newline and readlin a line of input. This still won't be ideal, because the normal input from the terminal doesn't lend itself to fancy menus, but it's a start. You should look into ncurses or possibly the options in <conio.h> if you want to write pretty DOS-style menus.
Anyway, here's a suggestion that should get you an idea:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int read_key()
{
char buf[40];
char key;
if (fgets(buf, sizeof(buf), stdin) == NULL) return -1;
if (sscanf(buf, " %c", &key) == 0) return 0;
return key;
}
int read_line(char *buf, int max)
{
int len;
if (fgets(buf, max, stdin) == NULL) return -1;
len = strlen(buf);
if (len) buf[--len] = '\0';
return len;
}
int main()
{
char buf[40];
int key;
int len;
printf("\nW e l c o m e !\n\n");
for(;;) {
printf(" (L) Look\n");
printf(" (R) Register\n");
printf(" (Q) Quit\n");
printf("\n");
key = read_key();
switch (key) {
case 'l':
case 'L':
printf("You are in the school library in a maze of "
"twisted aisles, all different.");
break;
case 'r':
case 'R':
printf("Enter your name:\n");
len = read_line(buf, sizeof(buf));
if (len < 0) goto quit;
if (len) {
printf("Your name is %d letters (and spaces) long.\n", len);
}
break;
case 'q':
case 'Q':
case -1:
quit:
printf("Goodbye.\n");
exit(0);
break;
default:
printf("Oh, the letter '%c'. That's not on the menu.\n", key);
}
printf("\n");
}
}
I haven't looked too closely at the rest of your code, but it doesn't look too solid to me. For example, the showAll function is horrid with a never-ending while loop and an ad-hoc fread where you should probably be using fgets. It is also customary to keey a dictionary in memory and commit the changes to disk after the program has terminated.