Math 211    Test 1, February 19, 1997 

Instructions.

Please enter your AFS-id and ID number.  

Problems 1 to 8 worth 10 points each. 

If you are asked for output, give your output in EXACTLY the
same way the computer will generate; the output should be
three lines or less, so you should have enough space for
each problem.

If you are asked to point out the errors of a program,
(a) list the line number, and then (b) correct the errors
by writing the correct version. 

Problem 9 worth a total of 20 points. Each sub-problem worth 
4 points.  Write your answer for each sub-problem.

The exam is given under the provision of the Honor Code.

Only the first page is to be handed in.



Yellow Version


Problem 1:

Instructions:  Give the output for the following program:

#include <stdio.h>

main()
{
      int i = 23, x = 0;

      printf("Just for Practice.\n");
      while (i > 1) {
          if (i%5 == 0) {
	          x += i;
                  printf("%d, ", x);
	          }
	  --i;
      }
      printf("x = %d\n", x);

      return 0;
}



Problem 2:

Instructions:  Give the output for the following program:

#include <stdio.h>

main()
{
    int digit = 7;
    while(digit >= 3)
          printf("%d", --digit);
    printf("\n");

    return 0;
}



Problem 4:

Instructions:  Give the output for the following program:

#include <stdio.h>
#include <ctype.h>

main()
{
       char ch;

       for ( ch = 'g'; ch >= 'a'; ch--){
           putchar(ch);
           putchar(toupper(ch));
           printf(", ");
       }
       printf("\n");

       return 0;
}



Problem 5:

Instructions:  Give the output for the following program:

#include <stdio.h>

main()
{
      int i, flag, x = 0;

      for (i = 1; i < 7; ++i)   {
           flag = i % 3;
           switch (flag) {
               case 0:
                   x += 3; break;
               case 1:
                   x++; break;
               default:
                   x += 10; break;
               }
           printf("%d, " , x);
      }

      printf("x = %d\n" , x) ;

      return 0;
}


Problem 3:

Instructions:  Give the output for the following program:

#include <stdio.h>

main()
{
        int  j = 7, k = 12;
        float  a;

        a = k/j;
        printf("a = %.2f, j = %d\n", a, j++);

        a = (float) k / j;
        printf("a = %.2f, j = %d\n", a, ++j);

        j--;
        a = (float) k / (float) j;
        printf("a = %.2f, j = %d\n", a, j);
        
        return 0;
}


Problem 6:

Instructions:  Give the output for the following program 
when the user gives 5 as input.


#include <stdio.h>
#define CONST 5

main()
{
        int sum = 0, n, k;
 
        printf( "Enter a decimal integer: " );
        scanf( "%d", &n );
 
        for ( k = 1; k < 4; k++){
             sum += n + CONST;
             }
        printf( "n = %d, sum = %d.\n", n, sum );
 
        if ( sum < 20 )
             printf( "The sum is small.\n" );
        else
             printf( "Oops, too big.\n" );
 
        return 0;
}


Problem 7:

Instructions:  The following program is supposed to print
the tenth digit of a two digit number.  However, there are
2 errors in the program. Although it compiles, the result 
is not as expected. 

Give the line number(s) where the errors occur, and give the
corrected code for that line.  



line
number

1.  #include <stdio.h>
2.  main()

3.  {
4.	int n, m;

5.	/* initialize and read in a value for n */

6.	printf("Enter a two-digits interger: ");
7.	scanf("%d", n) ;

9.  	/* Get the tenth digit */
10.	m = n / 10;

11.     printf("The tenth digit is: %d\n", &m);
 
12.     return 0;

13.  }



Problem 8.
Instruction:  The following program is supposed to convert
a letter grade to "Passing-Failing system".

However, there are 5 errors in the program so that it will
not even compile.  The compilier gives the following error
message:

undefined symbol: A    integral constant expression expected
undefined symbol: B    integral constant expression expected
duplicate case in switch: 1
undefined symbol: C    integral constant expression expected
duplicate case in switch: 1
undefined symbol: D    integral constant expression expected
duplicate case in switch: 1
undefined symbol: F    integral constant expression expected
duplicate case in switch: 1

Give the line number(s) where the errors occur, and give the
corrected code for that line.
 

line
number
1.  #include <stdio.h>
2.  #include <ctype.h>
3.  main()

4.  {

5.    char ch;

6.    printf("Please enter a grade (A, B, C, D, F): ") ;
7.    ch = getchar();
8.    ch = toupper( ch );

9.    switch( ch ) {
10.      case A: case B: case C: case D:
11.         printf("Good. You passed the course.\n");  break;
12.      case F:
13.         printf("Sorry. You failed the course.\n");  break;
14.      default:
15.         printf("Illegal letter grade.\n");  break;
16.        }

17.     return 0;

18.  }


Problem 9:

Give the answer for the variables after the assignment below:

(a)
 int i, j, k;
 i = 4; j = 2; k = 3;
 k++;
 i--;
 j *= k + i;   
 
Answer j = 

(b)
 char c1, c2, c3;
 c1 = 'a';  c2 = 'A';
 c3 = 'D' + c1 - c2 + 1;

Answer c3 =
(Your answer should be a character in ' ', remember the
answer is case sensitive).


(c) 
 int i, j, k;
 i = 3; j = 5; k=7;
 k =  i <= 2 ? j : i;

Answer k =

(d)
 float c = 10.0, interest = 0.01;
 float credit = 2.4, debt = 3.4;
 c *= interest + 1.0;
 c += credit - debt;
 
Answer c = 

(e) 
 int i = 0, j = 1, k = 3, n = 3;
 n = i <= j && k < n;

Answer n =