First C app please help

[zootreeves]

I've been messing around trying to learn glade/C and I'm trying to make a very simple calculator - just with two forms and it adds one to the other.

So I've created the UI with glade (see screenshot), but the program just crashes when I click apply (Add). Here's my callbacks.c file:

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <gnome.h>

#include "callbacks.h"
#include "interface.h"
#include "support.h"


void on_OK_clicked(GtkButton *button, gpointer user_data){
int numbone;
int numbtwo;
int output;


GtkWidget * entryone = lookup_widget(GTK_WIDGET(button), "entry3");
GtkWidget * entrytwo = lookup_widget(GTK_WIDGET(button), "entry4");
GtkWidget * entryout = lookup_widget(GTK_WIDGET(button), "EqualBox");


numbone = gtk_entry_get_text(GTK_ENTRY(entryone));
numbtwo = gtk_entry_get_text(GTK_ENTRY(entrytwo));

output = numbone + numbtwo;

gtk_entry_set_text(GTK_ENTRY(entryout),output);

}



The propblem I think is in this line:

output = numbone + numbtwo;

I can use:

output = numbone;

and I shows the first number in the total box, but It is when I try and add the number it goes wrong. I can't even use output = numbone + 2;

[zootreeves]

This is really frustrating. How to you add stuff?

If I do:
output= "2+2";

then it just puts 2+2 in the box, if I do

output= 2 + 2;

It crashes [-(

[sapo]

I dont know anything about C, but arent you trying to put a integer value in a string var?

Try using a int var or maybe convert integer to string :p

[zootreeves]

I new to the difference between int, char, var, I mostly use php so have never bothered with setting variable types.

I tried to use sprintf(output, "%", total); to convert the int to string, but it just crashes again.

To help find the error I tried this:
total = numbone + numbtwo;

printf("Number one = %d\n", numbone);
printf("Number two = %d\n", numbtwo);
printf("Number = %d\n", total);


Say If I put 3 in one box and 4 in the other I would expect it to say:
Number one = 3
Number two = 4
Number = 7

But whatever number I put in it outputs:
Number one = 135123592
Number two = 135131392
Number = 270254984

[rock freak]

are you getting any errors when you re make it / ciompile it

[lnostdal]

you're doing a lot of wierd things .. i'm not going to bother telling you the answers (knowledge != answers)

instead, look for "The C Programming Language" at Amazon.com or your local library.. they can probably order the book from an external library if they do not have it

[zootreeves]

Thanks for your replies. There are no errors during compilation, I am completely stumped...

Has anyone got the solution - I find it much easier to learn by example...

[David Marrs]

Check the stdlib (http://www.gnu.org/software/libc/) docs for atoi().

int i = atoi("5");

PS. atoi is deprecated, according to the manual. User strtol instead.

[rock freak]

well this sounds alot like my a level computing tasks for the coursework so yes i do no how to do it and i shall do a example for you if you wish so you still have to learn how to implement it into your own code!

I find that its a good elarnign way as long as you understand what does what!!!

tell me if you would like tht example ;)

[zootreeves]

Finally! I got it to work. Here's the code in case any beginners are after something similiar:

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <gtk/gtk.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>

#include "callbacks.h"
#include "interface.h"
#include "support.h"



void
on_Apply_clicked (GtkButton *button,
gpointer user_data)
{


int total;
int totaltxt;
char totalready[80];

GtkWidget *entry = lookup_widget(GTK_WIDGET(button), "entry4");
int *entry_text = gtk_entry_get_text(GTK_ENTRY(entry));

GtkWidget *entry2 = lookup_widget(GTK_WIDGET(button), "entry5");
int *entry2_text = gtk_entry_get_text(GTK_ENTRY(entry2));

GtkWidget *totalb = lookup_widget(GTK_WIDGET(button), "entry3");

long int number1 = strtol(entry_text, NULL, 16);
long int number2 = strtol(entry2_text, NULL, 16);
total = number1 + number2;

//print in terminal
printf("%d", total);
g_print(entry_text);
g_print(entry2_text);

totaltxt = "Total Is:";

sprintf(totalready, "%i", total);




gtk_entry_set_text(GTK_ENTRY(totalb),totalready);
}


I have also attached the glade file...

But now have a new problem, But i don't think it is to do with my code, I think ubuntu/gcc is setup wrong:

If I put: #include <iostream.h> in calbacks.c then i get:
callbacks.c:10:22: error: iostream.h: No such file or directory

I think this is the cause of why if i use cout is says it is not declared. Anyone have any ideas? Thanks

[jerome bettis]

iostream and cout are C++ things not C

you want to #include <stdio.h> and use printf() for output

[lnostdal]

if you want to use C++ compile your code with g++ instead of gcc, and remember that #include <iostream.h> is deprecated (old and non-standard).. you should use #include <iostream> instead

[rock freak]

i dont get what you need from

<iostream.h>

all you need is

#include <stdio.h>

unless there is more c code???

[zootreeves]

I was just messing around using different functions - but I didn't realise the tutorial I was reading was for C++.

The most annoying thing I have found about C so far is that when you try and look anything up on google there is no good documentation and because 'C' (It's not like 'C++' or 'Python') is such a broad term the documentation that is there is mixed up with other useless stuff.

[lnostdal]

I use the glibc manual and the man-pages for this: http://www.gnu.org/software/libc/manual/

You can also access the glibc-manual from the console by typing info libc (or from emacs too!)

Here:
http://www.gnu.org/software/libc/manual/html_node/Formatted-Output-Functions.html#Formatted-Output-Functions

then if you type man sprintf you get more details

[rock freak]

hey there if you need a nice C tht is a C reference libary not C++ or C#

I use this link and my c book

http://www.acm.uiuc.edu/webmonkeys/book/c_guide/