PNG dll required

[Gizmo]

use this:

scanf("%127s", this_is_a_string);

The '%127s' tells scanf to accept up to a maximum of 127 characters of input before terminating. It puts a terminating null char at the end of the string, which is why you use 127 instead of 128 (the size of the char array). Note that there is no guarantee that there will be 127 characters in the array, only that scanf will accept up to that many. If the user hits the enter key before the 127th character, then you will get input up to that many characters of input. You can use strlen() to determine exactly how many characters were entered if you are interested.

if("%s", this_is_a_string > 30) goto "printf", this_is_a_string;

Is not valid 'C' code. If anything, it looks like a combination of 'C' and Basic.

Also, as a matter of style, it is best to avoid goto. There is nothing you can do with goto in 'C' that you can't accomplish using another language construct, and in 99.999% of the cases, you will have code that is easier to maintain as well. (Not saying you can't use goto; there are some very rare situations where it makes sense. But you should ask yourself if using goto is the best way to solve your problem.)

[skool h8r]

Ok, thanks for that gizmo.

here's my complete code, some of the comments are there so that i can re-insert it if needed.

#include <stdio.h>

int main()
{
	char this_is_a_string[128];

    printf( "Welcome to AuthentiLog.\nTo initiate the login procedure\npress the enter key.", this_is_a_string );
    getchar();
    printf( "User name: " );
    scanf( "%s", this_is_a_string );
    printf( "welcome %s.\n", this_is_a_string );




    char input_errora[128];

	scanf( "%30s", this_is_a_string );

/*------
	if ( "%30s", this_is_a_string );
	printf( "\nInvalid Input, please enter a value less than 30 characters long\n", input_errora );
------*/





    char magic_string[128];

    printf( "Password: ", magic_string );
    scanf( "%s", &magic_string );
    getchar();
    printf( "Thankyou. ", magic_string );





	char input_errorb[128];

	scanf( "%30s", magic_string );

/*------
	if ( "%30s", magic_string );
	printf( "\nInvalid Input, please enter a value less than 30 characters long\n", input_errorb );
------*/





    char sir_madam[128];

    printf( "\nPlease enter verification string: " );
    scanf( "%s", sir_madam );
    getchar();
    printf( "Thankyou.", sir_madam );
    getchar();



	char input_errorc[128];

	scanf( "%30s", sir_madam );

/*------
	if ( "%30s", sir_madam );
	printf( "\nInvalid Input, please enter a value less than 30 characters long\n", input_errorc );
------*/



	char number_list_confirm[128];

    printf( "Please confirm the details below are correct.\n" );
    printf( "UserName: %s.\n", this_is_a_string );
    printf( "Password: %s.\n", magic_string );
    printf( "Verification: %s.\n", sir_madam );
    getchar();



	char enter_pin[128];

	printf( "please enter a pin number to confirm that they are correct.\n" );
	printf( "PIN:", enter_pin );
	scanf( "%s", enter_pin );
	printf( "\nYou entered %s\n", enter_pin );
	printf( "Press the enter key to confirm.\n\n" );
	getchar();



	char input_errord[128];

	scanf( "%30s", enter_pin );

/*------
	if ( "%30s", enter_pin );
	printf( "\nInvalid Input, please enter a value less than 30 characters long\n", input_errord );
------*/




/*---

    scanf( "%s", magic_string );
    printf( "PassNumber: %s", magic_string );
    getchar();
    scanf( "%s", sir_madam );
    printf( "Verification Number: %s", sir_madam );
    getchar();
---*/

    char string_final[128];
    //this code is wrong------->printf( "\n", this_is_a_string );
    //printf("%s\n", this_is_a_string);
	getchar();
    printf( "Thankyou for using AuthentiLog %s.", this_is_a_string );
    printf( "\nGoodbye %s.", this_is_a_string );
    getchar();
}

The user has to enter things twice though and it really is quite messed up.


Edit: I've sorted it out, if you enter more than 30 characters, it spreads into the password and verification field. i'll post source later if anyone wants it. Now i'm really happy because i'm really getting the hang of it, thanks to everyone, especially gizmo for the help with learning.

[Gizmo]

Originally Posted by Chesso

Search google for c++ data types. Also if you really despise char arrays you could always get somethign fo rit and include it so you can have string capability from the get go.

The C++ standard libary includes a string class. You can implement a safe string type in C, but its rather messy. C++ is a better way to go anyway, because then you have the ability to use classes and objects. (Not that you can't implement the same functionality using C, it's just easier with C++.)

[Gizmo]

Originally Posted by skool h8r

There is one thing i really want to learn though, how to make windows applications rather than the console application i made earlier.

For a windows application, you have to include some additional header files. A windows app is also a bit more complex. If you do straight Win32 API calls, then you have to have a winmain that gets called for initialization which registers your window class (basically your application name) and provides a pointer to your wndproc function. Wndproc is your windows message pump. Windows operates by passing messages back and forth between the OS and the app, and the message pump is where you make the decision about what do with the messages you get. This is usually implemented as a massive switch statement, and can have literally hundreds of cases associated with it.

If you use a framework class library like MFC or OWL (Borland's Object Windows Library, which I still love) all of this housekeeping stuff is done for you so that you can focus on the task at hand.

[skool h8r]

ah right. I know about the messages as when making Re-volt setup file, there were advanced options using calls and messages. Sounds a bit like my mobile/cell phone. I didn't use them but i am going to start lerning how to make windows apps soon. When i'm comfortable with C, i'll learn C++ but until then, learning C is my objective.

[skool h8r]

Right, i'm having problems with 'else' statements. here's what i've got so far:

if( "%s" == "scott");
printf( "You have the same name as the programmer of this application!\n");
	else
printf("welcome %s.\n", this_is_a_string);

The compiler is saying that else is an unrecognised statement and that on the last line, there's a missing semicolon before 'printf'. I know how to solve the semicolon problem but i have never seen a semicolon at the start of an expression, is it right? If i put it after the else, it's ok but the other error still occurs.

[Gizmo]

Originally Posted by skool h8r

Right, i'm having problems with 'else' statements. here's what i've got so far:

if( "%s" == "scott");
printf( "You have the same name as the programmer of this application!\n");
	else
printf("welcome %s.\n", this_is_a_string);

The compiler is saying that else is an unrecognised statement and that on the last line, there's a missing semicolon before 'printf'. I know how to solve the semicolon problem but i have never seen a semicolon at the start of an expression, is it right? If i put it after the else, it's ok but the other error still occurs.

if("%s" == "scott");

is an empty statement. The semicolon terminated the if statement, as it terminates all statements in 'C' and C++. You then followed that with the printf. If you had gotten the code to run, you would have discovered that the printf always executed, because you closed the if statement. The compiler then encountered the else clause, but had no if statement to associate it with.

Here's what you wanted to write:

if( "%s" == "scott")
    printf( "You have the same name as the programmer of this application!\n");
else
    printf("welcome %s.\n", this_is_a_string);

However, this code won't produce the expected results, because you aren't comparing a variable and a string literal; you are comparing two string literals. The above statement will always evaluate as false, and the else clause will always be executed. Instead, you need to use the 'C' standard library function strcmp (or stricmp, for case insensitive compare), like this:

if(0 == stricmp(this_is_a_string, "scott"))
    printf( "You have the same name as the programmer of this application!\n");
else
    printf("welcome %s.\n", this_is_a_string);

notice that I am using a comparison to 0 for the result of stricmp. It returns a negative number is string a is less than string b, 0 if they are equal, and a positive number is string a is greater than string b (a more complete explanation should be available in your compiler documentation). Since a value of 0 is the same as false in every compiler I have ever worked with, you could also write the if statement like this:

if(!stricmp(this_is_a_string, "scott"))
    printf( "You have the same name as the programmer of this application!\n");
else
    printf("welcome %s.\n", this_is_a_string);

The '!' symbol is C's logical negation operator (!false == true, and !true == false.) I wouldn't recommend writing the code this way, but it is certainly valid to do so.

[Gizmo]

Also, a couple of notes on coding style.

Every programmer develops a style of coding over a period of time that allows them to produce the most code with the least errors. There are some generally accepted style guides for each language, and 'C' is no exception. However, remember that they are guides, not rules. They exist because they have been found to be the most effective for most people. It is OK to disregard them or change them, but think about it very carefully before you do so.

Now, the style issue:

The following code is perfectly legal, and will compile

if(!stricmp(this_is_a_string, "scott"))
    printf( "You have the same name as the programmer of this application!\n");
else
    printf("welcome %s.\n", this_is_a_string);

However, if you go back somewhere down the line, and decide to add some code, you may be in for a nasty surprise.

if(!stricmp(this_is_a_string, "scott"))
    printf( "You have the same name as the programmer of this application!\n");
    printf("Because of this, you to be proclaimed as a great person!\n");
else
    printf("welcome %s.\n", this_is_a_string);

The code will no longer compile. Why? Because the semicolon at the end of the first printf statement terminated that portion of the if statement, so now the else clause has no where to go. To get around this, you include both printf statements in braces, like this:

if(!stricmp(this_is_a_string, "scott"))
{
    printf( "You have the same name as the programmer of this application!\n");
    printf("Because of this, you to be proclaimed as a great person!\n");
}
else
    printf("welcome %s.\n", this_is_a_string);

Now the code compiles and runs as you would expect. As a consequence, I tend to put braces in all of my if statements, even when they aren't syntactically required. It just makes things simpler later.

The other thing is, notice how I structured the test in the if statement? Let's use a different piece of code:

#define ONE 1
#define TWO 2

int something = ONE;

if(something == ONE)
    printf("One\n");
if(something = TWO)
   printf("Two\n");

This code prints the value of 'Two' every time it runs. Why? Because the second if statement assigns the value of 2 to something. Remember what I said earlier about 0 being false? Well, the flip side of that is that anything that is not 0 is true. (Remember !true == false, and !false == true? Well, if we #define 0 FALSE, then we can #define TRUE !FALSE). The if statement evaluates the result of the assignment, which is 2. Since 2 is not 0, the if is true, and the printf gets executed.

This all comes about because C uses == for comparison and = for assignment. There are a lot of debates about whether this is a good or bad thing, which we needn't get into here. However, to avoid this problem, I do the following:

#define ONE 1
#define TWO 2

int something = ONE;

if(ONE == something)
    printf("One\n");
if(TWO = something)
   printf("Two\n");

This code will fail to compile, because now I am trying to assign a value to a constant. Thus, by making a minor change in my coding style, I have allowed the compiler to check my code and make sure it is doing what I intended.

[skool h8r]

Right, is it possible to have a 'time-delay' style thing? Like if i want to write 'loading...' and then have it add a full stop every second for a set amount of full stops e.g. add one full stop per second and then after it has printed 5 full stops to the screen, write another message such as 'loading complete'. I am considering using the 'timer' function in time.h to do this but don't know if it will work. I know it is a little bit more advanced but i'm sure it can be done. I've got the idea of if and else statements now, thanks again gizmo.

[Gizmo]

You can use the Windows sleep() function to surrender control back to the OS for some period of time, but you have to include windows.h to use it, and your app is no longer portable. The only other way I know of would be to simply sit in a loop and call the clock() function until the specified time period has elapsed. As far as printing the dots is concerned, that's easy.

So, you would do something like this:

#include <time.h>
#include <stdio.h>
int main()
{
    clock_t ctTime;

    printf("waiting");
    ctTime = clock();
    ctTime += CLOCKS_PER_SEC;
    int nNumStops = 5;
    do
    {
        nNumStops--;
        printf(".");
        //empty while loop here
        //just to waste time
        while(ctTime < clock());

    } while(nNumStops > 0);//this while is actually a clause for the do loop
}

[skool h8r]

Ah right, i get it now. I've finished the program for now and i'll post it in the morning. Once again, thanks gizmo for all the help, now i've got the basics of it, i think i can start to work up from where i am now. And to think, it all started with me requesting a png dll! I can't make one yet but i can make something unique in C.

Thanks,
Scott.

[Kaitain]

Do the posix functions such as nanosleep() work in Windows?

[Gizmo]

If you have the Posix subsystem loaded they do (mostly), but that is part of the resource kit and has to be specifically installed, so it isn't on most systems. As far as what specifically is supported, I do not know, as I've never used it. Knowing MS I would say that it is the bare minimum required to be considered 'Posix Compliant'.

[Kaitain]

Hmm, tell me about it. Code that runs nicely in Solaris has less than predictable results in Linux, and gets spat out miserably by mingw

[Chesso]

Don't worry mate you'll get used to how if/then/else if/else statements work even if it is a bit annoyinh at first. I prefer my simple delphi as i don't have to use stupid bracket's even if it does look cleaner i use Begin and End.

Im pretty sure for a basic Windows gui you include <windows> or <windows.h> depends on the compiler but most just take the name without the extension these days. If you wan't to start on a windows gui best find a source code example of a skeleton one that explains bit by bit.

It took me hours to find one when i wanted to have a go at it but i found a good example eventually.

I think it's also always a good thing to indent if statment's in by one line unless inside another in which case you indent one line further. And unless an if is indented thus far i usually indent commands by 4 lines. Makes the code much more readable, extra spacing after some if statement's can help too so you don't put something in the wrong place for example:

 If () Then Begin
  If() Then Begin
   If () Then Begin
   
   End;
//Extra line here so you know where the if end's incase code need be put here later.
  End;
//Same here.
 End;

[Kaitain]

I like a lot of white space in my code. My indents are one tab and I leave two carriage returns between functions. Only function names are at position 1, all executable code starts with 1 tab input. It's a work of art

Mind you, I only really program 8051 (and now derivatives) assembler. I have the kit for 6800 and 6502 but haven't looked at it yet.

[skool h8r]

Right, here's the improved version i promised yesterday. i've only just got online because i've been out all morning sorting out some shoes for school and a few other things.

Anyway, the program is attached. I've put in messages that make it look like it copies files to memory but it doesn't, it's just to make it look more 'realistic'.

[arislestget]

awesome. nice man.