Using C language to use system calls Post: 302734115

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Homework and Emergencies Homework & Coursework Questions Using C language to use system calls Post 302734115 by Corona688 on Wednesday 21st of November 2012 03:53:45 PM

11-21-2012

Registered User

It's possible to do it either way. Line-by-line is probably easier.

Your using scanf incorrectly every time you use it. You can't store a string in a char, since a string is a char array, and you shouldn't be using scanf to read raw data. Read lines then feed them into sscanf, or your code may get stuck in infinite loops whenever the user types something wrong.

I'd do this:

Code:

while(1)
{
        char buf[512];
        int selection;
        if(fgets(buf, 512, stdin) == NULL) break; // Read line, quit on error
        // Convert line into number
        if(sscanf(buf, "%d", &selection) != 1)
        {
                fprintf(stderr, "you did not type a number\n");
                continue;
        }

        switch(selection)
        {
...
        }
}

Also, you cannot store an entire string inside a single character. You'll need to feed sscanf an array for the filenames. Something like this:

Code:

char fname[512];
printf("Please enter a filename:\n");
// Read a line
fgets(fname, 512, stdin);
// chop the newline off the end of the line
for(n=0; fname[n]; n++) if(fname[n] == '\n') fname[n]='\0';

System calls you'll need are unlink to remove files, open to read or create files, read to read from files, write to write to files, and close to close file descriptors once you're done.

Include files you'll need for all those are

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

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glutmenustatusfunc

glutMenuStatusFunc(3GLUT)					       GLUT						 glutMenuStatusFunc(3GLUT)

NAME

       glutMenuStatusFunc - sets the global menu status callback.

SYNTAX

       #include <GLUT/glut.h>

       void glutMenuStatusFunc(void (*func)(int status, int x, int y));
       void glutMenuStateFunc(void (*func)(int status));

ARGUMENTS

       func	 The new menu status (or state) callback function.

DESCRIPTION

       glutMenuStatusFunc  sets  the  global menu status callback so a GLUT program can determine when a menu is in use or not. When a menu status
       callback is registered, it will be called with the value GLUT_MENU_IN_USE for its value parameter when pop-up menus are in use by the user;
       and  the callback will be called with the value GLUT_MENU_NOT_IN_USE for its status parameter when pop-up menus are no longer in use. The x
       and y parameters indicate the location in window coordinates of the button press that caused the menu to go into use, or the location where
       the  menu  was  released  (may  be outside the window). The func parameter names the callback function. Other callbacks continue to operate
       (except mouse motion callbacks) when pop-up menus are in use so the menu status callback allows a program to  suspend  animation  or  other
       tasks  when menus are in use. The cascading and unmapping of sub-menus from an initial pop-up menu does not generate menu status callbacks.
       There is a single menu status callback for GLUT.

       When the menu status callback is called, the current menu will be set  to  the  initial	pop-up	menu  in  both	the  GLUT_MENU_IN_USE  and
       GLUT_MENU_NOT_IN_USE  cases.  The  current  window  will  be set to the window from which the initial menu was popped up from, also in both
       cases.

       Passing NULL to glutMenuStatusFunc disables the generation of the menu status callback.

       glutMenuStateFunc is a deprecated version of the glutMenuStatusFunc routine. The only difference is  glutMenuStateFunc  callback  prototype
       does not deliver the two additional x and y coordinates.

SEE ALSO

       glutCreateMenu, glutCreateWindow

AUTHOR

       Mark J. Kilgard (mjk@nvidia.com)

GLUT
									3.7						 glutMenuStatusFunc(3GLUT)