C / C++ / MFC

Re: Binary Tree traversal

13-Oct-09 7:03

See here.

I've also seen implementations where the tree was laying on its side. It's a recursive approach.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Alan Balkany15-Oct-09 4:40

Alan Balkany

15-Oct-09 4:40

First you need to learn how to draw lines on the screen. If you're using MFC, look at OnDraw and the CDC class. Then you can look at writing text if you need to do that.

For arranging the binary tree on the screen, a good approach is to space the leaf nodes out evenly horizontally. Then each parent node goes halfway between its sons, on the row above.

I have problem with C for passing ARGS to main function in LINUX

Mohamed_Khalil13-Oct-09 5:50

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 5:50

Hi guys ,

I've problem with C in Linux, and just i need to pass args to execvp(args[0],args) to the main function and after creating child process and the code is :

#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <unistd.h>
#define MAX_LINE 80

void setup(char inputBuffer[],char *args[],int *background)
{
int i;
int cmd=0;
int l;

  
scanf("%s",inputBuffer);//input command

if("%d",strlen(inputBuffer)>80)  //check the command; if the command >80 will give an error and exit the process,otherwise it will complete the process
{
 printf("error the maximum size is 80\n"); 
exit(-1);
}

else
{
  args  = &inputBuffer;
   
  }
    

}


int main(void)
{

char inputBuffer[MAX_LINE];
int  background =0;
char *args[MAX_LINE/2+1];
char *command;


while(1)
{
background=0;
printf("Command ->");
setup(inputBuffer,args,&background);

pid_t pChild;
pChild = fork();


if(pChild <0){
printf("Error\n");
exit(-1);
}

if(pChild==0)
{ 
execvp(args[0],args);
}


else {
if(background=1);

wait(NULL);

printf("Child process completed\n");
}
exit(0);
}
}

David Crow13-Oct-09 6:20

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:20

So what's the problem? Confused | :confused:

dr.nokia wrote:
if("%d",strlen(inputBuffer)>80)

What's this?

dr.nokia wrote:
if(removed=1);

Your compiler should at least be warning you about this, if not outright complaining.

Mohamed_Khalil13-Oct-09 6:25

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:25

Im trying to update the args to pass into main function to (execvp) and run the command for example

ls - 1

or sh> cat pro.c

just i need to pass args to the main function to execute the command Frown | :(

David Crow13-Oct-09 6:28

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:28

dr.nokia wrote:
just i need to pass args to the main function...

Then you're gonna need to change its signature to:

main( int argc, char *argv[] )

Mohamed_Khalil13-Oct-09 6:33

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:33

ok! i changed the signature but the output only "Child process completed")
Frown | :(

Mohamed_Khalil13-Oct-09 6:39

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:39

by the way : if(removed =1) it's if D'Oh! | :doh:

(background=1)

David Crow13-Oct-09 6:43

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:43

Until you have a firmer grasp of functions, pointers, arrays, etc, you'd be better served by simplifying your code down to something like:

void main( void )
{
    execvp("ls", "- 1"); // blocks
    printf("Child process completed\n");
}

Once you get that working, then you can start using scanf() to replace the string literals.

Richard MacCutchan13-Oct-09 6:39

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:39

The statement args = &inputBuffer; in the setup() function, does not change the args variable in main(). Also you have not split the input buffer into its separate components. I would spend some time parsing your input to ensure it's in the correct format before worrying about using the fork() and execvp() functions.

Mohamed_Khalil13-Oct-09 6:53

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 6:53

I did that it works fine but like execvp("ls",args);
not like your code execvp("ls","-1");
it's work perfect and execute the all ls command

but it's possible to put any command I prefer? for example ps -el or any another shell command for Linux O.S?

Confused | :confused:

Richard MacCutchan13-Oct-09 7:04

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 7:04

dr.nokia wrote:
not like your code execvp("ls","-1");

I didn't post any code Confused | :confused:

dr.nokia wrote:
but it's possible to put any command I prefer?

It's some while since I did this, or used Linux, but in theory I think you can put any command into the exec() functions. The key as always is getting your parameters organised correctly according to the version of the exec() call that you are making.

As I said before, I think the important thing is to get comfortable with parsing strings and using function calls and their parameters correctly. Once you have your head round those concepts then the second half is easy.

Mohamed_Khalil13-Oct-09 7:10

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 7:10

you mean to check my command then invoke it to execvp() ?

Richard MacCutchan13-Oct-09 7:20

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 7:20

dr.nokia wrote:
you mean to check my command then invoke it to execvp() ?

Well I'm not exactly sure what your level of expertise is, so I was really trying to suggest that you get comfortable with the simple things before moving to the more complex ones. The same as any learning process really.

Mohamed_Khalil13-Oct-09 7:25

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 7:25

Really I wana be very good in programming Frown | :(

if you have explanation about this and signals also and sources please get it to me Frown | :(

Mohamed_Khalil13-Oct-09 7:29

Re: I have problem with C for passing ARGS to main function in LINUX

13-Oct-09 7:29

Actually I need to very clear in C then coz im studying computer science then and im taking OOP and then I will teach my self C# and more advanced programming courses.

By the way the industry for programming what the most wanted programming languages in this days?

Richard MacCutchan13-Oct-09 9:12