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March 6th, 2005, 11:43 PM
#1
 Logic interruption
Greetings:
i have been working on this code for some time now, but I am stuck in a logic cavity: The program is a simple astronomy app which consults a local flatfile database as well as works simple statistics mathematics such as variance, deviation, range, means, etc. The problem is, there are just two initial choices available for the user, but only the first is accesible, while the second exists only in theory, closing the console if anything but the first choice is selected. There are if, else errors I am sure, but after a few days of working just on this coding problem, I am honestly stumped, lost. I have consulted many sites and sources for research, but alas, am no further to an improvement. Truly, I need someone to explain "if, else if, else" use to me once and for all, as I fear it has never been made clear to me in school up to this point.
(Note: code truncated for forum use \ code compiled in Dev-C++ compiler)
Code:
#include <stdio.h>
#include <conio.h>
#include <time.h>
#include <windows.h>
int main ()
{
int stats;
char choice;
{
printf("\nPlease select your area of interest: Galaxy Log OR Celestial Statistics.\n");
printf("\n (G)alactic Database \n (C)elestial Statistics\n");
printf("\nChoice:");
choice=getche();
}
if ('G' ==choice || 'g'==choice)
{
int num;
printf("\nPlease make a selection from the list below by entering a number from 1-10: ");
printf("\n________________________________________\n");
printf("\n 1.The Sun \n ");
printf("\n 2.Proxima Centauri\n ");
printf("\n 3.Barnard's Star \n ");
printf("\n 4.Wolf 359 \n ");
printf("\n 5.Lalande 21185 \n ");
printf("\n 6.Sirius \n ");
printf("\n 7.Luyten 726-8 AB \n ");
printf("\n 8.Ross 154 \n ");
printf("\n 9.Epsilon Eridani \n ");
printf("\n 10.Ross 248 \n ");
scanf("%d", &num);
switch (num)
{
/*-----------------------------------------*/
case 1:
FILE *stream1;
char line1[1000];
printf("\n You selected The Sun ...\n" );
printf("\n________________________________________\n");
Sleep(1000);
if( (stream1 = fopen( "1_Sun.txt", "r" )) != NULL )
{
if( fgets( line1, 1000, stream1 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line1);
fclose( stream1 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 2:
FILE *stream2;
char line2[1000];
printf("\n You selected Proxima Centauri ...\n" );
printf("\n________________________________________\n");
if( (stream2 = fopen( "2_Proxima Centauri.txt", "r" )) != NULL )
{
if( fgets( line2, 1000, stream2 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line2);
fclose( stream2 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 3:
FILE *stream3;
char line3[1000];
printf("\n You selected Barnard's Star ...\n" );
printf("\n________________________________________\n");
if( (stream3 = fopen( "3_Barnard's Star.txt", "r" )) != NULL )
{
if( fgets( line3, 1000, stream3 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line3);
fclose( stream3 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 4:
FILE *stream4;
char line4[1000];
printf("\n You selected Wolf359 ...\n" );
printf("\n________________________________________\n");
if( (stream4 = fopen( "4_Wolf359.txt", "r" )) != NULL )
{
if( fgets( line4, 1000, stream4 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line4);
fclose( stream4 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 5:
FILE *stream5;
char line5[1000];
printf("\n You selected Lalande 21185 ...\n" );
printf("\n________________________________________\n");
if( (stream5 = fopen( "5_Lalande 21185.txt", "r" )) != NULL )
{
if( fgets( line5, 1000, stream5 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line5);
fclose( stream5 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 6:
FILE *stream6;
char line6[1000];
printf("\n You selected Sirius ...\n" );
printf("\n________________________________________\n");
if( (stream6 = fopen( "6_Sirius.txt", "r" )) != NULL )
{
if( fgets( line6, 1000, stream6 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line6);
fclose( stream6 );
Sleep(20000);
break;
/*-----------------------------------------*/
case 7:
FILE *stream7;
char line7[1000];
printf("\n You selected Luyten 726-8 ...\n" );
printf("\n________________________________________\n");
if( (stream7 = fopen( "7_Luyten 726-8.txt", "r" )) != NULL )
{
if( fgets( line7, 1000, stream7 ) == NULL)
printf( "fgets error\n" );
else
printf( "%s", line7);
fclose( stream7 );
Sleep(20000);
break;
break;
/*-----------------------------------------*/
default:
puts("I'm sorry, but have made an invalid selection.");
Sleep(2000);
}
else
{
printf("\n You have chosen Celestial Statistics.\n");
printf("\n Celestial Statistics is an application\n");
printf("\n designed to calculate mean distances between bodies, \n");
printf("\n variations of the distance of stars, and more. \n");
printf("\n First, please choose your mode of calculation: \n");
printf("\n (1)Mode \n (2)Mean\n (3)Variance \n (4)Nothing \n ");
printf("\nChoice:");
stats=getche();
Sleep(20000);
}}}}}}}}}}}}}
"Nay, you love this present life!"
Save your keystrokes!
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March 7th, 2005, 11:39 AM
#2
Re: Logic interruption
I'm not sure I understand your question. The code looks fine to me.
Basically, if tests a condition. Control path through the code is "altered" based on that condition.
Code:
if (cond1)
{
// Execute this block if 'cond1' is true
}
else if (cond2)
{
// Execute this block if 'cond2' is true AND 'cond1' is false
}
else
{
// Execute this block if BOTH 'cond1' and 'cond2' are false
}
Viggy
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