Thread: Login code help

Need help, the warnings are: "initilization makes integer from pointer without cast" "comparison between pointer and integer" "comparison with string literal results in unspecified behaviour" If you could also tell me what those errors mean so I can fix it myself next time that would be great.

Code:

#include <stdio.h>


int main() {
char log_status = "";
char username = "";
char password = "";
char password_r = "H";
printf("Hello and welcome to Visualizer Creator! If you have an account, please type login. If not, please type register.");
scanf(" %s ", &log_status);


if (log_status == "login") {
    printf("Input Username: \n");
    scanf(" %s ", &username);
    printf("Input Password: \n");
    scanf(" %s ", &password);
    printf("Welcome to the program!");
}
else if (log_status == "register") {
    printf("Input Username: \n");
    scanf(" %s ", &username);
    printf("Input Password: \n");
    scanf(" %s ", &password);
    printf("Please input your Password again: \n");
    scanf(" %s ", &password_r);


    if (password == password_r) {
        printf("Thank you for registering!");
    }


    else {
        printf("Error, password must be the same both times");
    }




}




return 0;
}

Code:

char log_status = "";
char username = "";
char password = "";
char password_r = "H";

You are not allocating space for the strings.

Code:

char log_status[256] = "";
char username[256] = "";
char password[256] = "";
char password_r[256] = "H";

Code:

if (log_status == "login") {

You cannot compare strings using the '==' operator, you need strcmp();

You should use fgets() rather than scanf() to input strings, but be aware that fgets() brings in the newline at the end of the string which you will need to remove. (Please don't use gets())!!!

OK, I fixed some of the things, this is the code now. There are still errors: "warning, passing argument 2 of fgets makes integer from pointer without a cast" "note: expected int but argument is of type char (*) [10]" "error: too few arguments to function fgets" and more. Please help IDK exactly how fgets works!

Code:

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


int main() {
char log_status[10] = "";
char username[10] = "";
char password[10] = "";
char password_r[10] = "H";
printf("Hello and welcome to Visualizer Creator! If you have an account, please type login. If not, please type register.");
fgets(" %s ", &log_status);


if (strcmp(log_status, "login") == 0) {
    printf("Input Username:");
    fegets(" %s ", &username);
    printf("Input Password: \n");
    fgets(" %s ", &password);
    printf("Welcome to the program!");
}
else if (strcmp(log_status, "register") == 0) {
    printf("Input Username: \n");
    fgets(" %s ", &username);
    printf("Input Password: \n");
    fgets(" %s ", &password);
    printf("Please input your Password again: \n");
    fgets(" %s ", &password_r);


    if (password == password_r) {
        printf("Thank you for registering!");
    }


    else {
        printf("Error, password must be the same both times");
    }




}




return 0;
}

Before you use a Standard Library function, you need to look at how the function should be used. Most of your errors are related to fgets().

If you are using gcc, then run this command:

Code:

$ man fgets

Or else look at the same command online. The same with any other function.

You don't need the '&' before "username", and other char arrays. "username" rather than "&username" in the fgets() calls. An array name is the address of the first element of the array.

ok i remove the & sign but im still getting a bunch of errors, like "passing argument 2 of fgets creates integer from pointer without a cast" and for line 11 "too few arguments in fgets" as well as, somehow on line 354 (which doesn't exist???) "note: declared here" i have no idead how/what those errors mean and whati have to do to fix them. Please help! (code is the same as above, but the & signs have been removed from fgets)

OK, thank you very much. I didn't see the link the first time I read your reply lol. I changed the fgets(), and now there are no more errors. Unfortunately, nothing is being printed after I type login or register when I execute the program. DO you know how I can fix this?

Code:

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


int main() {
char log_status[256] = "";
char username[256] = "";
char password[256] = "";
char password_r[256] = "H";
printf("Hello and welcome to Visualizer Creator! If you have an account, please type login. If not, please type register.");
fgets(log_status, 256, stdin);


if (strcmp(log_status, "login") == 0) {
    printf("Input Username: ");
    fgets(username, 256, stdin);
    printf("Input Password: ");
    fgets(password, 256, stdin);
    printf("Welcome to the program!");
}
else if (strcmp(log_status, "register") == 0) {
    printf("Input Username: ");
    fgets(username, 256, stdin);
    printf("Input Password: ");
    fgets(password, 256, stdin);
    printf("Please input your Password again: ");
    fgets(password_r, 256, stdin);


    if (strcmp(password, password_r) == 0) {
        printf("Thank you for registering!");
    }


    else {
        printf("Error, password must be the same both times");
    }




}




return 0;
}

Originally Posted by Joeyfish_13

OK, thank you very much. I didn't see the link the first time I read your reply lol. I changed the fgets(), and now there are no more errors. Unfortunately, nothing is being printed after I type login or register when I execute the program. DO you know how I can fix this?

Yes, as I said before, fgets() will bring in the newline at the input string. You will need to remove the newline BEFORE you compare the input string against a constant string.

ok how do i remove the newline

Thank you so much! It works perfectly now! One last thing, would you be able to explain what that command means/does so I can now how to use it later? Thanks!