C Booking Issues - c

Question

typedef struct contact {
char firstname [40];
char lastname [40];
char address [100];
char phone[10];
}contact;
int main ()
{
FILE *pFile;
contact entry = {"", "", "", ""};
int choice;
char cont = 5;
pFile = fopen("C:\\contacts.txt", "w+");
if(!pFile){
printf("File could not be open");
return 1;
}
printf("Choose a selection\n\n");
printf("1. Enter First Name\n");
printf("2. Enter Last Name\n");
printf("3. Enter Address\n");
printf("4. Enter Phone Number\n\n");
scanf( "%d", &choice);
while (choice = 1|2|3|4|cont){
if (choice = 1){
printf ("First name: ");
fgets(entry.firstname, sizeof(entry.firstname),stdin);
}
else if(choice = 2){
printf ("Last name: ");
fgets(entry.lastname, sizeof(entry.lastname),stdin);
}
else if(choice = 3){
printf ("Address: ");
fgets(entry.address, sizeof(entry.address),stdin);
}
else if (choice = 4){
printf ("Phone number: ");
fgets(entry.phone, sizeof(entry.phone),stdin);
}
else
printf("Exiting");
break;
fwrite (&entry, sizeof (struct contact), 1, pFile);
printf ("Would you like to enter a new contact? (y/n)");
scanf ("%d", &cont);
if (cont = 'n'|'N')
return 0;
}
fclose(pFile);
getchar();
return 0;
}
is my code at the moment. Each time I give any option 1,2,3,4, put in a entry and press enter the window closes. I'm unsure if the logic makes sense and any suggestions are welcome but it "seems" okay to me but obviously I need another set of eyes. I want it where I don't have to enter all entries for every person I put in the file. Also, to note, I initially cont to 5 just because it was complaining.. bad practice I know. Any helpful information is appreciated

Answer 1

Your program ends because the break; isn't in the scope you think it is:
else if (choice = 4){
printf ("Phone number: ");
fgets(entry.phone, sizeof(entry.phone),stdin);
}
else
printf("Exiting");
break;
Even though you've indented the break, it doesn't belong to the else clause. So no matter what happens in the if/else block, the break gets executed and your program breaks out of the loop and ends.
To fix it, add braces to enclose the break inside the scope of the else.:
else if (choice = 4){
printf ("Phone number: ");
fgets(entry.phone, sizeof(entry.phone),stdin);
}
else
{
printf("Exiting");
break;
}
And once you fix that, this line will cause your program to terminate because it always evaluates to true and returns from main:
if (cont = 'n'|'N')
return 0;
You want that line to say
if (cont == 'n' || cont == 'N')
return 0;
These fixes will at least stop your program from terminating, but as others have pointed out there are numerous logical errors elsewhere that will prevent it from doing what you want.

Answer 2

For example, the following line:
while (choice = 1|2|3|4|cont){
belies a misunderstanding of some fundamental concepts.
First = is the assignment operator. The above code, among other things, changes the value of choice. Use == for equality comparison.
Second, the | operator is a bitwise or. The value of 1|2|3|4|5 is 7 (I'll leave it to you to figure out why sometime). Instead, use || like this:
while (choice == 1 || choice == 2 || choice == 3 || choice == 4 || choice == cont) {
There are other similar errors throughout your code.

Answer 3

A single = does assignment in C. if (a = 5) { /* always executed! */ } sets a to 5 and then executes the if-branch because a = 5 evaluates to 5 which is considered true.
You want == which compares values. Thus:
if (choice = 1){
Should be
if (choice == 1){
Another thing:
while (choice = 1|2|3|4|cont){
Does not do what you think it does. It's actually computing the bitwise or of 1, 2, 3, 4 and cont. (So just changing = to == wouldn't be sufficient.) You need to compare each value in turn:
while (choice == 1 || choice == 2 || choice == 3 || choice == 4 || choice == cont){
Also notice the use of || (logical OR) instead of bitwise or.
EDIT: The reason your program prematurely exits is because of the following:
else
printf("Exiting");
break;
You're missing curly braces ({ and }), so it actually means the following (despite misleading indention):
else
printf("Exiting");
break;
Your code probably has more errors.

Answer 4

By using if (choice = 1) you are saying "If I change choice to 1" which is virtually guaranteed to work, but it destroys the previous value choice held.
You want to start off with if (choice == 1) which means "If I compare choice to 2, is this equal?`.