UMBC CMSC201, Computer Science I, Spring 1994 Sections 0101, 0102 and Honors

Final Exam A, Short Answer Section

Short Answers, 4 points each

• There are no intentional syntax errors in this section. So, ``Syntax Error --- no output is produced'' is not the correct answer for any of the questions. No credit will be given for such a response.
• Mark your final answers clearly.
• If you need more space use the back of the pages.
• To receive more partial credit, show your work.

1. This question tests your knowledge of global variables and lexical scoping. What is the output of the following program?

     #include <stdio.h>
     
     /* Global Variables */
     int a = 2, b = 4, c = 8 ;
     
     int foobar(int b) {
        int a ;
   
        a = b + c ;
        b = 2 * a ;
        c = b + 1 ; ;
        printf("foobar: a = %d, b = %d, c = %d\n", a, b, c) ;
        return(b) ;
     }
     
     main() {         
        a = foobar(c) ;
        printf("main: a = %d, b = %d, c = %d\n", a, b, c) ;
     }
   

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2. This question tests your knowledge of nested for loops. Please put carriage returns in the proper places. What is the output of the following code?

     int i, j;
     
     for (i = 0; i <= 2; i++) {
        for (j = 0; j <= 2; j++) { 
   	if ( i * i < j ) 
   	   printf("X") ;
   	else
   	   printf("O") ;
         }
         printf("\n") ;
     }
   

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3. This question tests your knowledge of pointers and parameter passing by reference. What is the output of the following program?

     int f(int x, int *p, int *t) {
     
        x = x + 1 ;
        *p = 2 * *p ;
        *t = 3 * *t  ;
        x = x + *p + *t ;
        return(x) ;
     }
     
     main() {
       int a = 1, b = 2, c = 3 ;
       
       a = f(a, &b, &c) ;
       printf("First Call: a = %d, b = %d, c = %d\n", a, b, c) ; 
   	   
       c = f(a, &b, &b) ;
       printf("Second Call: a = %d, b = %d, c = %d\n", a, b, c) ;
       
     }          
   

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4. This question tests your ability to work with characters and strings. What is the output of the following program?

     #include <stdio.h>
     #include "genlib.h"
     #include "simpio.h"
     #include "strlib.h"
   
     main() {
        int i, start, stop  ;
        string str ;
     
        str = "Our zip code is 21228." ;
        
        for (i = 0 ; str[i] != '\0' ; i++) {
   	if ( str[i] > 'w' ) break ;
        }
        start = i ;
        for (i = start ; str[i] != '\0' ; i++) {
   	if ( str[i] >='0' && str[i] <= '9' ) break ;
        }
        stop = i ;
        printf("%s\n", SubString(str, start, stop) ) ;
     }
   

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5. Write a simple loop which prints out the following sequence of numbers:

         4 8 16 32 64 128
   

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6. Rewrite the following loop without using the break statement. (Your code should be equivalent to the given code.)

     string str ;
     int i ;
   
     i = 0 ;
     str = GetLine() ;
     while ( str[i] != '\0' ) {
        if (str[i] == 'a') break ;
        i = i + 1 ;
     }
     printf ("Answer: %d\n", i) ;
   

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7. Write a function Occurrence which takes two arguments, a string and a character, and returns the number of times the character appears in the string. For example, Occurrence("Senselessness",'s') should return 6.

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