How to create login and password?

hi guys...

Im currently doing a project on a search and sort student database.Im required to create login and password for the users before he can enter the database.May i know how can i do that in C programming?

Also, there are 3 categories of users----> Students, Lecturers and Guests.

The criterias are:
For Student: He can only see his own info only, not others.
For Lecturer: He can see all in database.
For Guest:He cannot see the student's grades.

In the question given, there's only 13 students in the database.What is the optimal way to implement this database?
m planning to use sequential search + arrays + structures.Is it good?

Hope to get some clue here...As my project is gonna due at the end of this month!thanks alot..

That sounds like a good way to do it.

Something like this . . .

Code:

struct student_t {
    char name[BUFSIZ], password[BUFSIZ];
} user[13];

for(x = 0; x < 13; x++) {
    if(student == user[x]) {}
}

Thanks for replying me, dwks...

Code:

if(student == user[x]) {}

For the above code, what should i include in between the curly braces?
Should i initialize student ?

U can store all student related info here.

Code:

struct student_info {
 int rollno;
 char name[30];
 /* Other required fields*/
};

All passwords & username fields stay here

Code:

struct authentication {
char username[10],password[10];
int category;  /* 0 = student,1=teacher,2=guest */
};

Once user gets login then call display function with rollno & category,

Code:

void display(int rollno,int category) { 
/* here u can write conditions for viewing i.e. if user is student then he will see only his data */
 for(x = 0; x < 13; x++) {
    if(rollno == user[x].rollno) { /* display all structure fields */
    }
  }

/* And so on for other categories */
}

if we consider the database is sorted according to roll no then u can acquire data in single shot just by indexing array with key as rollno




Thanks & Regards
Vinit

thanx alot Vinit!

I guess i kinda understand bout how it functions.But still have to try it myself..

My friend has suggested that I should use file to create this student database,he said it will be better because arrays has temporary memory.What do you think?
If file is better, how can i create a database using file?How many files do i need, as there are 3 different conditions for 3 different types of user?I don't know how to set the conditions...

Sorry for asking oo much here, im a newbie who know very little, maybe anyone can kindly give me some good website to refer regarding my project..Thanks a million!

Yes indeed files will provide persistant storage.
U can use following file functions
fopen(); //opening file
fread(); //read from file
fwrite(); //write to file
fclose(); //close file
find their help & use them.

#include<stdio.h>
#define MNAME 20

struct Login{
char name[MNAME];
char password[MNAME];
};

int main(void){

struct Login student[3]={{"sherwi","8379008"},{"chris","smileyshen"},{"sh erwi10","cspang86"}};
struct Login lecturer[2]={{"Ian","Chai"},{"hcling","hc988"}};
struct Login query;

int user,i;

printf("Login as...\n");
printf("[1]Student [2]Lecturer [3]Guest\n");

scanf("%d",&user);

switch(user){

case 1: case 2:
printf("Username:");
scanf("%s",query.name);
printf("Password:");
scanf("%s",query.password);

for(i=0;i<3;i++){{
if(query.name==student[i].name)
printf("Login Successful");
}
if(query.name!=student[i].name)
printf("Wrong username or password");
exit(1);
}
break;

case 3:
printf("You can enter without login");

break;

default:
printf("Invalid input");
exit(1);

break;
}

return 0;
}


[QUOTE]

This is what i've done for the login part.But i cant seem to get the right output.I think most probably my if condition is wrong.Can anyone tell me what is the right condition ??

well u should compare string using strcmpi() function,& store those password & username in seperate file.

Code:

 if (strcmpi(query.name,student[i].name) == 0) {
 printf("\nLoging successful");
}

In case strcmpi gives error use strcmp instead.

case 1: case 2:
printf("Username:");
scanf("%s",query.name);
printf("Password:");
scanf("%s",query.password);

for(i=0;i<3;i++){
if(strcmp(query.name,student[i].name)==0 && strcmp(query.password,student[i].password)==0)
printf("Login Successful");
}


break;


ok, i've changed to this...But one question, how do i tell the program to exit when the username and password is wrong?

and for the type of user, instead of typing 1,2 or 3 or any other integers, when i type a character or a string, it will proceed to asking for username and password when it should be an invalid input.Do u know what's wrong?

Code:

 for(i=0;i<3;i++){
if(strcmp(query.name,student[i].name)==0 && strcmp(query.password,student[i].password)==0)
{ printf("Login Successful"); }
else
{
 if (i == 2) /*its the 3rd try and failed */
 { return 0; }
}