where is my indefinite loop here?

[pancho]

this is supposed to be a multiplication program.. it compiles well but when I run it an indefinite loop is caused. can't see where. heeelp! i've been doing this for 2 days!....how I create the responses with a function void message(answer) ????? thanks...

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

int main()

{

int x, y, chosenoption, answer1, response, option;

srand( time( NULL ) );

printf( "\nLet's learn how to multiply.\n" );
printf( "Choose an option from below:\n" );
printf( "Type 1 for a single digit multiplication\n" );
printf( "Type 2 for a two digit multiplication\n" );
printf( "Type -1 to end program.\n \n");
scanf("%d", &chosenoption);

while(chosenoption != -1) {
if (chosenoption == 1){

x = ( rand() % 10 );
y = ( rand() % 10 );

printf( "How much is %d times %d? \n", x,y );
scanf("%d", &answer1);
}

if (chosenoption == 2){

x = 10 + ( rand() % 90 );
y = 10 + ( rand() % 90 );

printf( "How much is %d times %d? \n", x,y );
scanf("%d", &answer1);
}

if (answer1 == x*y )
response = 1;

else
response = 0;

option = 1 + ( rand() % 4 );

while ( response == 1 ) {
switch (option) {

case 1:
printf( "Very good!\n" );
break;

case 2:
printf( "Excellent!\n" );
break;

case 3:
printf( "Nice work!\n" );
break;

case 4:
printf( "Keep up the good work!\n" );
break;

}
}

while ( response == 0 ) {
switch (option) {

case 1:
printf( "No. Please try again.\n" );
break;

case 2:
printf( "Wrong. Try one more time.\n" );
break;

case 3:
printf( "Don't give up.\n" );
break;

case 4:
printf( "No. Keep trying.\n" );
break;

}
}

printf( "Let's learn how to multiply.\n" );
printf( "Choose an option from below:\n" );
printf( "Type 1 for a single digit multiplication\n" );
printf( "Type 2 for a two digit multiplication\n" );
printf( "Type -1 to end program.\n \n");
scanf("%d", &chosenoption);

}

return 0;
}

[Govtcheez]

while(chosenoption != -1) {
if (chosenoption == 1){

x = ( rand() % 10 );
y = ( rand() % 10 );

printf( "How much is %d times %d? \n", x,y );
scanf("%d", &answer1);
}

You only ask for chosenoption before this, so if they put anything in besides -1, that's going to loop infinitely.

[pancho]

nop...the loop is when the responses appear...for example if i answer correctly it will loop with excellent! forever......how do i correct that?

[Govtcheez]

Whoops - you're right, I counted the braces wrong. Your problem's the same type of thing, though.

while ( response == 0 ) { 
switch (option) { 

case 1: 
printf( "No. Please try again.\n" ); 
break; 

case 2: 
printf( "Wrong. Try one more time.\n" ); 
break; 

case 3: 
printf( "Don't give up.\n" ); 
break; 

case 4: 
printf( "No. Keep trying.\n" ); 
break; 

} 
}

::double checks braces::
There's no way for response to change inside the loop - that's why it loops forever. Use if statements instead.

if ( response == 0 ) { 
switch (option) { 

case 1: 
printf( "No. Please try again.\n" ); 
break; 

case 2: 
printf( "Wrong. Try one more time.\n" ); 
break; 

case 3: 
printf( "Don't give up.\n" ); 
break; 

case 4: 
printf( "No. Keep trying.\n" ); 
break; 

} 
}

[pancho]

thanks!!!! .......the program is running properly ...
well, the grand final question:

the program ask the following feature which I dont know how to do:


*use the following function: void message(int answer); function message should accept as parameter an integer value, which should be 1 if the answer is correct, and 0 if the answer is wrong. It should then print the appropiate message..


how in the hell i do that....the instructor did not explain that well the part of function prototypes and function calls..please this is the last question!

[Deckard]

Something like this?

void message( int answer )
{
  if ( answer )
    printf( "Correct\n" );
  else
    printf( "Incorrect\n" );
}

[pancho]

no....with the responses that are in the switch structures above...please! thanks

[Deckard]

Hmm, perhaps you could take a stab at it and post your code if you get stuck. If that doesn't work, maybe you could provide us with directions to your school and the contact information for a good plastic surgeon so that Cheez or I are able to complete the class for you.

[pancho]

here is.,...the problem is that it always prints the wrong responses even though i perform the multiplications well....whats wrong?


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

void Message(int);
int main()

{

int x, y, chosenoption, answer1, response, option;

srand( time( NULL ) );

printf( "\nLet's learn how to multiply.\n" );
printf( "\nChoose an option from below:\n" );
printf( "Type 1 for a single digit multiplication\n" );
printf( "Type 2 for a two digit multiplication\n" );
printf( "Type -1 to end program.\n \n");
scanf("%d", &chosenoption);

while(chosenoption != -1) {
if (chosenoption == 1){

x = ( rand() % 10 );
y = ( rand() % 10 );

printf( "\nHow much is %d times %d? \n", x,y );
scanf("%d", &answer1);
}

if (chosenoption == 2){

x = 10 + ( rand() % 90 );
y = 10 + ( rand() % 90 );

printf( "\nHow much is %d times %d? \n", x,y );
scanf("%d", &answer1);
}

Message(response);
option = 1 + ( rand() % 4 );

if ( response == 1 ) {
switch (option) {

case 1:
printf( "Very good!\n" );
break;

case 2:
printf( "Excellent!\n" );
break;

case 3:
printf( "Nice work!\n" );
break;

case 4:
printf( "Keep up the good work!\n" );
break;

}
}

if ( response == 0 ) {
switch (option) {

case 1:
printf( "No. Please try again.\n" );
break;

case 2:
printf( "Wrong. Try one more time.\n" );
break;

case 3:
printf( "Don't give up.\n" );
break;

case 4:
printf( "No. Keep trying.\n" );
break;

}
}

printf( "\nLet's learn how to multiply.\n" );
printf( "\nChoose an option from below:\n" );
printf( "Type 1 for a single digit multiplication\n" );
printf( "Type 2 for a two digit multiplication\n" );
printf( "Type -1 to end program.\n \n");
scanf("%d", &chosenoption);

}

return 0;
}

void Message( int answer )
{
int x,y;

if (answer == x*y )
answer = 1;

else
answer = 0;

}

[Deckard]

Originally posted by pancho

void Message( int answer )
{
  int x,y;

  if (answer == x*y )
    answer = 1;
  else
    answer = 0;
}

Pancho, x and y are not initialized. I suspect you wanted them to retain the values of the x and y variables from main(). You may want to review your textbook for discussions on variable scope.

Also, consider using the message() function in a different way. Instead of using message() to determine if the answer was correct, decide if the answer was correct beforehand, and then let message() print the success/failure message as your homework instructs.

/* in main() */
if ( x * y == answer1 )
  message( 1 ); /* Success */
else
  message( 0 ); /* Failure */

.
.
.

void message( int answer )
{
  if ( answer )
    printf( "Correct\n" );
  else
    printf( "Incorrect\n" );
}

If you are hell-bent on having the pseudo-random success/failure messages, move your rand() statement and switches into message().