What do I do now? - c

Question

It may be really simple, but I don't really know what to do now.
I just recently got in programming and I thought I should start by learning C, I know a few stuff here and there but I just recently got into this problem and I can't figure it out.
Im trying to make a register/login system that stores the credentials into strings using scanf(), I don't really know how to get the login part to work. Do I need to create more strings and store the input there? Or how can I compare the user's input to the value in the strings?
My code is currently looking like this:
#include<stdlib.h>
#include<time.h>
char user[30] = "";
char password[30] = "";
char yn[30] = "";
char Y[1] = "Y";
char N[1] = "N";
int main() {
printf("Register\n");
printf("The User or Password can't be longer than 30 characters\n");
printf("User: \n");
scanf("%s", &user);
if (user == NULL)
printf("User can't be empty\n");
else
printf("Password: \n");
scanf(" %s", &password);
if (password == NULL)
printf("Password can't be empty\n");
printf("User saved as: \n");
printf("%s\n", &user);
printf("Password saved as: \n");
printf("%s\n", &password);
printf("Is this correct?\n");
printf("Y/N\n");
scanf("%s", yn);
if(yn == Y){
printf("\e[1;1H\e[2J");
}
if(yn == N){
printf("Restarting...");
}
printf("Login\n");
printf("User: \n");
}
It all works well (except I can't figure out how to clear the console before asking to log in, this wont work printf("\e[1;1H\e[2J");), I even managed to print out the user's input to the console for him to make sure its correct and I made a (Y/N) thingy. Can someone help me please?

Answer 1

You can create functions instead of having them all in the main.
Create a register function that saves the data and a login function that asks for data as parameters and the call it in the main.
Maybe you can create a simple menu.

Answer 2

When you first learn a language, you discover certain patterns of how it can be used. Some of your problems come from overusing patterns where they don't make sense.
For example, you know you can compare two variables with == but that compares values, and in some cases you are comparing references as if they were values. References are memory addresses, and if you have two letters Y in RAM then they are distinct, having two different references, even if their value is the same.
Since a lot of your processing uses strings, read through the functions available when you #include <string.h> You will hear a lot about how some of these are unsafe to use; for now I recommend skipping safety arguments as they make more sense after you know how to call the functions.
For example
if (yn == Y) {
is not going to give you the desired result, but
if ( strcmp( toupper( yn[0] ), "Y" ) == 0 ) {
will give you the desired result. As in most cases, there are other ways to write the same logic; but, for those who want to offer more efficient ways of checking yn, this is an example designed to show off string functions.
Strings in C are not single values. They are an address (sometimes called a reference) to a pieced of memory, which if you keep reading char-by-char should eventually end in a NULL character, a char containing the number 0. This means that they cannot be compared directly as in yn == Y because you are comparing two memory addresses, not two sequences of chars.
The above example is a simplification of what strings can be. It's a good enough of a definition for a beginner; but, over time you will find that this definition is very old, and has been revised over time. The problem is that a char can only hold 8 bits, so when more than 256 distinct values were needed, a solution was created to hold more values.
The first solution was to use a "wide character" called a wchar, which has the type of wchar_t. This is like a char, but it holds 16 bits. This started the whole "char" vs "wchar_t" problems. For now you can ignore them, but be aware that if you ever work with wchar_t you need wchar compatible functions.
The second solution was to introduced Unicode, which provides enough characters that nearly every language can be written within Unicode, even most dead languages, emojis, upside down text, etc. Unicode doesn't have a single way of representing its characters, but there are two popular ones for the beginning programmer. UTF-32, which used 32 bytes for each character, is popular because it is easy to program. UTF-8 is popular because it is the effective "correct choice" for the Internet due to it extending ASCII and being the format of the Internet.
Once you get familiar with strings, you might want to spend some quality time with UTF-8.
Good luck.