Approximately a Final Exam CPSC 206

Transcription

1 Approximately a Final Exam CPSC 206 Sometime in History based on Kelley & Pohl Last name, First Name Last 4 digits of ID Write your section number: All parts of this exam are required unless plainly and explicitly announced by the instructor during class. Each True/False problem is to be answered T for true or F by circling the appropriate letter. For multiple choice questions the answer is to be entered by circling the label. The worth of individual problems is shown like [9]. If you have a question about a problem, write the question, the answer you are assuming, and continue. In other words, do not ask it aloud!! Verbosity is discouraged. We have provided sufficient lined space for answers. In some cases we may have provided more than enough. Written answers should be written in good English. Neatness counts and we reserve the right to assign lower grades for sloppiness, much lower! Do not remove the staple or tear exam packet apart! Calculators, PDAs, CD players, radios, and headphones are not allowed! K, M, G may be used. If so, K = 2 10 = 1024, M = 2 20 = , G = 2 30 = Aggies do not lie, cheat, or steal and do not tolerate those who do! I have obeyed the Aggie code of honor in my answers on this exam. Signature Page Total Max Pts Your Points

2 True/False. 1. [1] T F The C type char defaults to signed char. The integral values of variables of this type may be negative which allows handling of special things like EOF. 2. [1] T F The absence of a semicolon after the closing right parenthesis of a function header indicates that this header is a prototype. 3. [1] T F The code fragment char p[]="howdy boys " "and girls\n"; printf("%s", p); will compile cleanly and run cause two lines of output. 4. [1] T F Functions in C are call-by-value. The values of arguments are passed to the functions. If an argument is a pointer, changes made to the values pointed to are temporary and disappear when the return is made. 5. [1] T F The code fragment return return_value; is always a legal substitute for exit(return_value); but may cause different results in execution. 6. [1] T F When control is returned from a function it passes to the next statement after the one from which the call to the function was made. 7. [1] T F The name of an array when used without subscripts can be used in all places that a pointer can be used. 8. [1] T F These initializations are legal in C: int *p = &i, i = 65535; 9. [1] T F The function isalnum returns true if the argument is an alphabetic character or numeric digit but returns false if it is an underscore. 10. [1] T F The following is a valid C statement with a precise meaning: d = a + (b = c); Your instructor has told you that the Ags we tell jokes about would write such. 11. [1] T F These numeric constants are all the same in C: 16, 018, and 0x [1] T F The output of printf("%d",sizeof( z )); and printf("%d",sizeof( \0 )); are the same. 13. [1] T F On the computers we are using in our labs, pointers to all variables, regardless of type, always use 4 bytes of memory. 14. [1] T F The string./ at the start of a file name stands for the parent directory. 15. [1] T F The following loops are identical in execution results (execution time is not considered) i=0; while( logical expression ){ valid C code; i++;} for( i=0; logical expression; i++){ valid C code; } The logical expression and valid C code; segments are identical. 2

3 16. [1] T F The function main is special in C in that the linker marks it as the point to begin execution but main is not a keyword. 17. [1] T F The C output conversion specification of %4.3f used with a variable of type float will output a string of numbers with up to four digits to the left of the decimal point, the decimal point, and three digits to the right of the decimal point. 18. [1] T F The order of a the cases of a switch statement must always be in increasing order and the default case should be the last. 19. [1] T F Ordinary text files on Windows systems and unix systems are the same in content since both use the standard ASCII coding system. 20. [1] T F The command gcc -Wall -c junk.c will create the executable file a.out when code problems cause warnings but not when there is an error. 21. [1] T F A return statement is required for all C functions except for those of type void. 22. [1] T F A potential line of C source contains the assignment short_string = "Howdy Ags!"; Assume the declaration char *short_string preceeded the assignment. The effect of the assignment statement is to copy the contents of the string constant to the address represented by the pointer short_string. 23. [1] T F The C input conversion specification of %lf can be used with variables of type float and double. 24. [1] T F A potential line of C source contains char a_short_string[] = "Short"; This causes a_short_string to be a pointer to to the first of six bytes of memory. 25. [1] T F The -Wall switch on the gcc compilation command line instructs the computer to build a symbolic wall, as in firewall, around the compilation process. 26. [1] T F A declaration int jj, *ii = NULL; followed by jj = *ii; sets the value of jj to zero. 27. [1] T F The command gcc -c junk.c can create the object file junk.o and an executable a.out 28. [1] T F In C, a value zero is considered as false. Positive and negative values are considered to be true. 29. [1] T F It is a convention to usually give macros UPPERCASE names when using the #define 30. [1] T F The i++ operation cannot be substituted for the ++i in the following code fragment and without changing the results. #include <stdio.h> int main(void){ int i, product=1; for (i=1; i<=10; ++i){ printf(" %d", product); product = product*i; if( i%5 == 0 ) printf("\n"); } } 3

4 Multiple Choice. 31. [3] Which of the following is a valid preprocessor directive which will insert a header file containing prototypes for standard trigonometric functions? a. #include <stdlib.h> b. #include <stdio.h> c. #include <maths.h> d. #include <ctype.h> e. #include <trig.h> f. None of the earlier 32. [3] What is the value of count after execution of the for loop? int sum = 0, count; for (count=0; count <=8; count++) {if (count==3) continue; sum+=count; } a. 0 b. 33 c. 12 d. 17 e. the value of count is not defined after the for loop 33. [3] Part of a function contains this code: char *str_operation( char *shh, const char tsch[] ){ The programmer considers using the expression tsch++. a. This is not allowed because of the const b. This is not allowed at all. in the function statement c. This is allowed except as the target of an d. This is allowed as long as it is not assignment. preceeded by an *. 34. [3] Given the following declaration: int a[16384]; which of the following is not a valid C expression? a. a - 1 b. a c. none should be done d. a[32000] 35. [3] Given the following array declaration and initialization: int a[5] = {0, 1, 2}; what is the value of a[5]? a. 0 b. 1 c. 2 d. None of these is correct. 36. [3] Which one is correct? In C, a string created by the declaration char str[]="01234"; a. cannot be changed to a shorter string b. cannot be changed at all c. cannot be changed to a longer string d. is an array of five characters. 4

5 37. [3] Given the following declaration: int a[10]; which of the following gives the the fifth element of a? a. *(a + 4) b. (a[4]) c. All the others d. *(&a[3] + 1) 38. [3] When an array is passed as a parameter to a function, what is actually passed? a. all elements of the array are copied into b. the array name is a pointer to the [1] the address space of the function element of the array and this address is copied into the address space of the function c. the array name is a pointer to the first d. none of the above. element of the array and this address is copied into the address space of the function 39. [3] What would be the output produced by the following code fragment? int i; for (i = 3; i > 0; --i); printf("%d+", i-1); a. -1+ b c d [3] Which of the following will produce a compiler error? a. void fun1(int a) { printf("%d", a); return a; } c. int fun1(int a) { printf("%d", a); return a; } b. void funct1(void) { int a=1; printf("%d", a); } d. int funct1(void) { int a= A ; return a; } 41. [3] In general, when a double and int variables are combined in a single expression then a. there is a syntax error, because double and int variables cannot be combined in one expression without casting b. both values are converted automatically to int double to increase precision c. the expression is evaluated without any conversion d. the value of type double is converted automatically to type int before the expression is evaluated e. the value of type int is converted automatically to type double before the expression is evaluated 42. [3] Why does the following piece of code give a compile time error? const int round = 20000; round++; a. integer is not a proper variable name b. the value is too big for a variable of type int c. round is a keyword in C d. it attempts to increment a variable declared as const 5

6 Problems Remember the verbosity instructions. 43. [4] The use of the scanf() function normally requires that we use the address operator (&). Why is this not required when we input a string with a statement scanf("%s", string_name); 44. [4] What is (a) casting in C and (b) the use of casting a pointer to items of type void? 45. [4] Write the output from the following code fragment. Be careful in showing spacing and output of new lines. int i=0, j=1; i = 2 && (j <= 2); printf("%d %d ", i, j); (i == 0) && (j!= 2); printf("%d %d ", i, j); i = 0 (j == 4); printf("%d %d ", i, j); (i = 2) (j = 6); printf("%d %d ", i, j); 46. [4] Write the output from this code in the space provided. Be careful in showing spacing and output of new lines. #include <stdio.h> int main(void){ int i; for (i=0; i<4; i++) printf("%c", M +i+32); for (i=0; i<4; ++i) printf("%c",( m -i)%128); return 0; } 6

7 47. [15] Document and write a program that will print the contents of a structured file. The program shall be named in to print and the input file shall be on the command line and extracted through the use of the argc/argv mechanism. Each line of the file shall contain four items each related to a city. These are: quality of life indicator, an integer [0...10] name, College Station for example population, an integer without commas, etc. county, Deaf Smith for example These items shall have at least one space separating them from the previous item. Extract each of these items from the input and output them in an aligned manner. The population shall not exceed 10,000,000. The maximum length of city and county names is 32 characters including imbedded spaces. Document the program carefully but not verbosely. Select meaningful variable names. State any standard library header files that must be included. 7

8 48. [15] Write and document a function ripple that has one argument which is a string. The function will output to stdout. The first line of output will be the input string. The second line will be like the first but the first character will be moved to the end of the string. When the strings are long it will give a ripple or streaking appearance on output. If the string is ABC/ the output would be like: ABC/ BC/A C/AB /ABC The number of lines output is the length of the string argument. The function does not have a return value. The function must not change the value(s) of the string argument. Document the function carefully but not verbosely. Select meaningful variable names. State any standard library header files that must be included. 8

9 49. [15] A program is to be written and documented to perform the actions described below. A linked list has been input with each element being of the type StrinG, a struct. The length element is identical to the strlen of the string s element. The next element points to the next item in the linked list and is NULL in the last element of the linked list. The value of head points to the first element of the linked list. The structure used is: typedef struct{char *string_s; int length; struct StrinG *next;} StrinG; StrinG *head=null, *p, *temp; int i, n; The program is to print a list of the data in the linked list. The length shall be output right justified in four spaces and the string left justified with one space separating it from the length. After output of the list, output an annotated number of elements in the list. Document the program carefully but not verbosely. Select meaningful variable names. State any standard library header files that must be included. 9