Unclear pointer and array Post: 302884188

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Top Forums Programming Unclear pointer and array Post 302884188 by Don Cragun on Saturday 18th of January 2014 08:14:10 AM

01-18-2014

Registered User

Try this instead:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define IOBufLen        100

char *substring(size_t start, size_t stop, const char *src, char *dst, size_t size)
{
    unsigned int count = stop - start;
    if (count >= --size) {
        count = size;
    }
    sprintf(dst, "%.*s", count, src + start);
    return dst;
}

int main(int argc, char **argv)
{
    char *text=(char*)malloc(IOBufLen);  //Line 40, change to text[100] will work
    char *a=(char*)malloc(IOBufLen);   //Line 41, change to a[100] will work
    int start, end;

    if (argc != 4) {
        printf("Error! Usage:\n\t \
argv[0]=program;\n\t \
argv[1]=input string\n\t \
argv[2]=start_position of string\n\t \
argv[3]=end_postion of string\n");

        return 1;
    }

    strncpy(text, argv[1], IOBufLen - 1); // -1 to be sure text is null terminated.
    start = atoi(argv[2]);
    end = atoi(argv[3]);

    printf("substring = \"%s\"\n", substring(start, end, text, a, IOBufLen));

    return 0;
}

Do you see why these changes make it work?

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LEARN ABOUT DEBIAN

wmanager

WMANAGER(1)						    BSD General Commands Manual 					       WMANAGER(1)

NAME

     wmanager -- choose a window manager and launch it

SYNOPSIS

     wmanager [OPTIONS ...]

DESCRIPTION

     The wmanager program displays a choice of the window managers listed in the ~/.wmanagerrc file.  When one is picked, the related command is
     written to standard output, intended to be used by shell scripts.	If the program is exited without choosing a window manager, ``-1'' is
     written to standard output.

     -fg COLOR
	     Set the foreground color.

     -bg COLOR
	     Set the background color.

     -bg2 COLOR
	     Set the widget background color

     -di[splay] host:n.n
	     Set the X display.

     -dn[d], -nod[nd]
	     Enable/disable drag & drop, probably does nothing.

     -g[eometry] WxH+X+Y
	     Set the window size and location.

     -i[conic]
	     Start as iconified.

     -k[bd], -nok[bd]
	     Enable/disable keyboard support.

     -na[me] CLASSNAME
	     Set the X window class.

     -s[cheme] SCHEME
	     Unknown, probably does nothing useful.

     -ti[tle] WINDOWTITLE
	     Set the window title.

     -to[oltips], -not[ooltips]
	     Enable/disable tooltips, probably does nothing.

EXAMPLE

     To start using wmanager, create a ~/.wmanagerrc file - generally with wmanagerrc-update(1) - and add something like the following at the end
     of your ~/.xsession file:

	   WM="$(wmanager -geometry +570+585)"
	   ...
	   exec $WM

     See also wmanager-loop(1) for a nicer way to start wmanager.

SEE ALSO

     wmanager(1), wmanager-loop(1), wmanagerrc-update(1), X(7x)

HISTORY

     The wmanager program was written by Meik Tessmer in 1999.	This manual page was originally written in perldoc format by Tommi Virtanen in
     2000, and converted to mdoc format by Peter Pentchev in 2008.

AUTHORS

     The wmanager program - Meik Tessmer <fuller@daemogorgon.net>.

     The manual page - Tommi Virtanen <tv@debian.org> and Peter Pentchev <roam@ringlet.net>.

BSD
								   May 22, 2008 							       BSD