Math Quiz program

**Zhen Wei** · 08-04-2017

I am programming a math quiz program for the college assignment below are a part of my code, the question is if user key in a char for the answer the program goes wrong, how to detect if the user keyed in char so i can send a message to user and say "Please enter a digit"

Code:

do    {
        no1 = rand() % 50 + 1;
        no2 = rand() % 50 + 1;
        pcAns = no1 + no2;


        printf("%d + %d = ", no1, no2);
        scanf("%d", &userAns);
         
        if (pcAns == userAns)
        {
            printf("Congratulation, your have entered the correct answer!!\n");
            mark = mark + 10;
        }
        else
            printf("Sorry the correct answer is %d \n", pcAns);


        count++;
    } while (count <= 10);

**GReaper** · 08-04-2017

To do that, you need to check the return value of scanf. It returns the number of successfully read items (or EOF).

In your case, if scanf returns something other than 1, you need to clear the remaining input and ask for a digit.

**Zhen Wei** · 08-04-2017

Originally Posted by GReaper

To do that, you need to check the return value of scanf. It returns the number of successfully read items (or EOF).

In your case, if scanf returns something other than 1, you need to clear the remaining input and ask for a digit.

i tried this its not working properly tho

Code:

do    {
        no1 = rand() % 50 + 1;
        no2 = rand() % 50 + 1;
        pcAns = no1 + no2;
        test:
        printf("%d + %d = ", no1, no2);
        scanf("%d", &userAns);
         
        if (scanf("%d", &userAns) == 1)
        {
            if (userAns == pcAns)
            {
                printf("Congratulation, your have entered the correct answer!!\n");
                mark = mark + 10;
            }
            else
                printf("Sorry the correct answer is %d \n", pcAns);
        }
        else if (scanf("%d", &userAns) != 1)
        {
            printf("Please enter yur answer in digit form");
            goto test;
        }
        count++;
    } while (count <= 10);

**Salem** · 08-05-2017

> else if (scanf("%d", &userAns) != 1)
This should be just an else, as in

Code:

else {
    int ch;
    while ( (ch=getchar()) != '\n' && ch != EOF );  // throw away the line
    printf("Please enter yur answer in digit form");
}

Also, you only call scanf ONCE to read a number, not three times as in your code.

> goto test;
Don't use goto's to make a while loop.

Code:

do {
  // prompt etc
} while ( userAns != pcAns );

**Zhen Wei** · 08-05-2017

Originally Posted by Salem

> else if (scanf("%d", &userAns) != 1)
This should be just an else, as in

Code:

else {
    int ch;
    while ( (ch=getchar()) != '\n' && ch != EOF );  // throw away the line
    printf("Please enter yur answer in digit form");
}

Also, you only call scanf ONCE to read a number, not three times as in your code.

> goto test;
Don't use goto's to make a while loop.

Code:

do {
  // prompt etc
} while ( userAns != pcAns );

initially my code is this

Code:

do
	{
		no1 = rand() % 51 + 50;
		no2 = rand() % 51 + 50;
		pcAns = no1 + no2;


		printf("%d + %d = ", no1, no2);
		scanf("%d", &userAns);


		if (pcAns == userAns)
		{
			printf("Congratulation, your have entered the correct answer!!\n");
			mark = mark + 10;
		}
		else
			printf("Sorry the correct answer is %d \n", pcAns);


		count++;
	} while (count <= 10);

everything runs fine, but if user enter an alpha the program goes wrong how should i fix that

**Zhen Wei** · 08-05-2017

i need to test wether the user entered digit or an alpha

**Salem** · 08-05-2017

Like this

Code:

int scanStatus = scanf("%d", &userAns);
if ( scanStatus == 1 ) {
  // check userAns
} else if ( scanStatus == 0 ) {
  // get rid of the junk characters
} else if ( scanStatus == EOF ) {
  // user has lost interest in your quiz and has quit
}

**Zhen Wei** · 08-05-2017

owh so we need to declare snother variables to store and see wether the scan status is 1(yes) or 0(no)?

**Zhen Wei** · 08-05-2017

Originally Posted by Salem

Like this

Code:

int scanStatus = scanf("%d", &userAns);
if ( scanStatus == 1 ) {
  // check userAns
} else if ( scanStatus == 0 ) {
  // get rid of the junk characters
} else if ( scanStatus == EOF ) {
  // user has lost interest in your quiz and has quit
}

Code:

do
	{
		no1 = rand() % 50 + 1;
		no2 = rand() % 50 + 1;
		pcAns = no1 + no2;
		printf("%d + %d = ", no1, no2);
		scanf("%d", &userAns);
		 
		if (scanStatus == 1)
		{
			if (userAns == pcAns)
			{
				printf("Congratulation, your have entered the correct answer!!\n");
				mark = mark + 10;
			}
			else
				printf("Sorry the correct answer is %d \n", pcAns);
		}
		else if (scanStatus == 0)
		{
			printf("Please enter yur answer in digit form");
		}
		count++;
	} while (count <= 10);

i changed the code to this but the output is
Please enter 1, 2, 3 or 41
You have selected ADDITION
Please select a level of difficulty: 1-Beginner, 2-Intermediate, or 3-Advance
1
1
ADDITION BEGINNER SELECTED
Please answer the 10 quetions given
16 + 50 = a
Sorry the correct answer is 66
50 + 22 = Sorry the correct answer is 72
11 + 28 = Sorry the correct answer is 39
13 + 40 = Sorry the correct answer is 53
30 + 40 = Sorry the correct answer is 70
44 + 2 = Sorry the correct answer is 46
23 + 25 = Sorry the correct answer is 48
3 + 25 = Sorry the correct answer is 28
34 + 10 = Sorry the correct answer is 44
26 + 22 = Sorry the correct answer is 48
YOUR TOTAL SOCORE IS 0/100
I am sorry, you does not perform well in this level, whould you like to restart the level? 1(yes)/2(no)
Press any key to continue . . .

**Salem** · 08-05-2017

You forgot to add this line!

while ( (ch=getchar()) != '\n' && ch != EOF ); // throw away the line

**Zhen Wei** · 08-05-2017

add at? and whats this line for?

**Zhen Wei** · 08-05-2017

i added it infinite loop happens

**Salem** · 08-05-2017

One can only guess as to what you've done wrong.
Post your latest code.

**Zhen Wei** · 08-05-2017

Code:

	do
	{
		no1 = rand() % 50 + 1;
		no2 = rand() % 50 + 1;
		pcAns = no1 + no2;
		printf("%d + %d = ", no1, no2);
		scanf("%d", &userAns);
		 
		if (scanStatus == 1)
		{
			if (userAns == pcAns)
			{
				printf("Congratulation, your have entered the correct answer!!\n");
				mark = mark + 10;
			}
			else
			{
				printf("Sorry the correct answer is %d \n", pcAns);
			}
		}
		else if (scanStatus == 0)
		{	
			int ch;
			while ((ch = getchar()) != '\n' && ch != EOF);
			printf("Please enter yur answer in digit form\n");
		}
		count++;
	} while (count <= 10);

i change something and the infinite loop disappear here is the output
Please enter 1, 2, 3 or 4
1
You have selected ADDITION
Please select a level of difficulty: 1-Beginner, 2-Intermediate, or 3-Advance
1 //i ned to type the choice here twice in order to sleect
1
ADDITION BEGINNER SELECTED
Please answer the 10 quetions given
23 + 17 = a //after i typed 'a' all of the other questions just pop out
Sorry the correct answer is 40
6 + 9 = Sorry the correct answer is 15
20 + 10 = Sorry the correct answer is 30
4 + 26 = Sorry the correct answer is 30
48 + 40 = Sorry the correct answer is 88
5 + 14 = Sorry the correct answer is 19
47 + 5 = Sorry the correct answer is 52
43 + 14 = Sorry the correct answer is 57
15 + 31 = Sorry the correct answer is 46
5 + 9 = Sorry the correct answer is 14
YOUR TOTAL SOCORE IS 0/100
I am sorry, you does not perform well in this level, whould you like to restart the level? 1(yes)/2(no)
Press any key to continue . . .

**Salem** · 08-05-2017

You need to pay close attention to the detail.

Code:

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

int main ( ) {
  int mark = 0;
  int count = 0;
  do
  {
      int no1 = rand() % 50 + 1;
      int no2 = rand() % 50 + 1;
      int pcAns = no1 + no2;
      printf("%d + %d = ", no1, no2);
      int userAns;
      int scanStatus = scanf("%d", &userAns); //!! yes, you forgot this assignment

      if (scanStatus == 1)
      {
          if (userAns == pcAns)
          {
              printf("Congratulation, your have entered the correct answer!!\n");
              mark = mark + 10;
          }
          else
          {
              printf("Sorry the correct answer is %d \n", pcAns);
          }
      }
      else if (scanStatus == 0)
      {
          int ch;
          while ((ch = getchar()) != '\n' && ch != EOF);
          printf("Please enter yur answer in digit form\n");
      }
      count++;
  } while (count <= 10);
  printf("You scored mark %d in %d attempts\n", mark, count);
}

Results

Code:

$ gcc bar.c
$ ./a.out 
34 + 37 = 55
Sorry the correct answer is 71 
28 + 16 = a
Please enter yur answer in digit form
44 + 36 = a
Please enter yur answer in digit form
37 + 43 = 80
Congratulation, your have entered the correct answer!!
50 + 22 = 72
Congratulation, your have entered the correct answer!!
13 + 28 = 41
Congratulation, your have entered the correct answer!!
41 + 10 = 51
Congratulation, your have entered the correct answer!!
14 + 27 = 38
Sorry the correct answer is 41 
41 + 27 = 68
Congratulation, your have entered the correct answer!!
23 + 37 = 60
Congratulation, your have entered the correct answer!!
12 + 19 = 31
Congratulation, your have entered the correct answer!!
You scored mark 70 in 11 attempts

Thread: Math Quiz program

Thread Tools

Search Thread

Display

Math Quiz program

Similar Threads

urgent need hlp..i'm develop a math quiz program thy was several error

urgent need hlp..i'm develop a math quiz program thy was several error

quiz program

Math Quiz Program Help

making a math quiz program

Tags for this Thread