Programming Forums > Application Development > C++

Option_Explicit · Dec 28th, 2004, 3:42 AM

Come on, I know you guys know what it means.

-Mike

Ravilj · Dec 28th, 2004, 4:34 AM

Option Explicit: All they saying is if you want read in a single key from the keyboard ie: user input than use getChar( ). Here is an example:

(Toggle Plain Text)

char c;
printf( "Are you sure you want to exit: [Y/N]");
c = getChar( );

if ( c == 'Y' ) 
{
// exit program
 return 0;
}

if ( c== 'N' ) 
{
// do something else
}

putChar( c ); Is just used to display the character stored in c on the screen.

Option_Explicit · Dec 28th, 2004, 2:43 PM

I started to re-read it and it made a bit more sense, but your explanation clarified almost all of it. Thanks a lot Ravilj, this section makes a lot more sense now.

-Mike

Option_Explicit · Dec 29th, 2004, 4:24 PM

I have another question! I got more into the getchar and putchar commands and wrote the example code out. Supposedly it counts input lines but I'm not sure what exactly the program does. If anyone could clarify, it would be helpful.

(Toggle Plain Text)

#include <stdio.h>

main()
{
     long nc;
     
     nc = 0;
     while (getchar() != EOF)
        ++nc;
     printf("%1d\n", nc);
}

-Mike

Tama · Dec 29th, 2004, 6:09 PM

>Supposedly it counts input lines
A line is any sequence of characters ending with '\n'. The code as posted counts the number of characters, not the number of lines.

>while (getchar() != EOF)
getchar reads a character. If it's anything but the macro EOF (which designates an error or the end of input) then nc is incremented.

If you want to count the number of lines then this would be more appropriate:

(Toggle Plain Text)

#include <stdio.h>

int main(void)
{
 long int nl = 0; /* Counter for the lines */
 int ch;     /* Used to save the input character for testing */

 /* Read characters until EOF and save them in ch */
 while ((ch = getchar()) != EOF) {
  /* Is ch an end of line marker? */
  if (ch == '\n')
   ++nl;
 }
 /* Match the format modifier with the variable type. */
 /* %ld is used for long int, not %d */
 printf("# of lines: %ld\n", nl);

 /* Always return a value! */
 return 0;
}

Option_Explicit · Dec 31st, 2004, 3:59 AM

Thank you Tama; I was actually looking at the wrong page when I entered the previous code, so it makes much more sense now. Thank you for clarifying this for me. Oh and the book I am using never mentioned returning zero, but I understand what it does, so I shall make sure I include that in my writing.
-Mike

bl00dninja · Dec 31st, 2004, 9:41 AM

i personally use Dev-C++ as an editor and i use borland (free command-line tools) as a compiler. ooble has posted a reply from me earlier on this forum about a simple way to configurate borland so that it is very simple to use.

Dec 28th, 2004, 4:34 AM	#12
Ravilj Programmer Join Date: Sep 2004 Location: JHB , South Africa Posts: 79 Rep Power: 5	Option Explicit: All they saying is if you want read in a single key from the keyboard ie: user input than use getChar( ). Here is an example: (Toggle Plain Text) char c; printf( "Are you sure you want to exit: [Y/N]"); c = getChar( ); if ( c == 'Y' ) { // exit program return 0; } if ( c== 'N' ) { // do something else } char c; printf( "Are you sure you want to exit: [Y/N]"); c = getChar( ); if ( c == 'Y' ) { // exit program return 0; } if ( c== 'N' ) { // do something else } putChar( c ); Is just used to display the character stored in c on the screen. __________________ Ravilj's OpenGL Terrain aka WinTerrain Last Updated: 17/01/2005!

Dec 29th, 2004, 4:24 PM	#14
Option_Explicit Programmer Join Date: Dec 2004 Posts: 31 Rep Power: 0	I have another question! I got more into the getchar and putchar commands and wrote the example code out. Supposedly it counts input lines but I'm not sure what exactly the program does. If anyone could clarify, it would be helpful. (Toggle Plain Text) #include <stdio.h> main() { long nc; nc = 0; while (getchar() != EOF) ++nc; printf("%1d\n", nc); } #include <stdio.h> main() { long nc; nc = 0; while (getchar() != EOF) ++nc; printf("%1d\n", nc); } -Mike

Dec 29th, 2004, 6:09 PM	#15
Tama Programmer Join Date: Dec 2004 Posts: 35 Rep Power: 0	>Supposedly it counts input lines A line is any sequence of characters ending with '\n'. The code as posted counts the number of characters, not the number of lines. >while (getchar() != EOF) getchar reads a character. If it's anything but the macro EOF (which designates an error or the end of input) then nc is incremented. If you want to count the number of lines then this would be more appropriate: (Toggle Plain Text) #include <stdio.h> int main(void) { long int nl = 0; /* Counter for the lines / int ch; / Used to save the input character for testing / / Read characters until EOF and save them in ch / while ((ch = getchar()) != EOF) { / Is ch an end of line marker? / if (ch == '\n') ++nl; } / Match the format modifier with the variable type. / / %ld is used for long int, not %d / printf("# of lines: %ld\n", nl); / Always return a value! / return 0; } #include <stdio.h> int main(void) { long int nl = 0; / Counter for the lines / int ch; / Used to save the input character for testing / / Read characters until EOF and save them in ch / while ((ch = getchar()) != EOF) { / Is ch an end of line marker? / if (ch == '\n') ++nl; } / Match the format modifier with the variable type. / / %ld is used for long int, not %d / printf("# of lines: %ld\n", nl); / Always return a value! */ return 0; }

Dec 31st, 2004, 9:41 AM	#17
bl00dninja Programming Guru Join Date: Oct 2004 Location: namespace std Posts: 1,246 Rep Power: 5	i personally use Dev-C++ as an editor and i use borland (free command-line tools) as a compiler. ooble has posted a reply from me earlier on this forum about a simple way to configurate borland so that it is very simple to use. __________________ i put on my robe and wizard hat... Have you ever heard of Plato, Aristotle, Socrates?...Morons.

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Dec 28th, 2004, 3:42 AM	#11
Option_Explicit Programmer Join Date: Dec 2004 Posts: 31 Rep Power: 0	Come on, I know you guys know what it means. -Mike

Dec 28th, 2004, 2:43 PM	#13
Option_Explicit Programmer Join Date: Dec 2004 Posts: 31 Rep Power: 0	I started to re-read it and it made a bit more sense, but your explanation clarified almost all of it. Thanks a lot Ravilj, this section makes a lot more sense now. -Mike

Dec 31st, 2004, 3:59 AM	#16
Option_Explicit Programmer Join Date: Dec 2004 Posts: 31 Rep Power: 0	Thank you Tama; I was actually looking at the wrong page when I entered the previous code, so it makes much more sense now. Thank you for clarifying this for me. Oh and the book I am using never mentioned returning zero, but I understand what it does, so I shall make sure I include that in my writing. -Mike

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