c-quiz.md

C (Programming Language)

Q1. Which Code sample will eventually cause the computer to run out of memory?

• [x]

while(1)
{
    char *smallString = (char *) malloc(10);
}

• [ ]

long long number = 1;
    while(1)
    number *= 2;

• [ ]

while(1)
{
    char hugeString[1000000L];
    memset(hugeString, 0, 1000000L);
}

• [ ]

while(1)
{
    long *bigArray = (long *) malloc(sizeof(long) * 1000);
    memset(bigArray, 1000000, 1000);
    free(bigArray);
}

Q2. What will this code print on the screen?

int f1 (int a, int b)
{
    if (a > b)
    {
        printf("A is greater than B\n");
        return 1;
    }
    else
    {
        printf("B is greater than A");
        return 0;
    }
}

main()
{
    if (f1(20,10) || f1(10,20))
        printf("C is fun!\n");
}

• [x]

A is greater then B
C is fun!

• [ ]

A is greater then B
B is greater then A
C is fun!

• [ ]

A is greater then B
B is greater then A

• Nothing is printed on Screen

Q3. What is the name for calling a function inside the same function?

• recursion
• subfunction
• inner call
• infinite loop

Q4. What does the declaration of variable c2 demonstrate?

main(){
    char c1 ='a';
    char c2 = c1+10;
}

• character arithmetic
• undefined assignment
• type conversion
• invalid declaration

Q5. A pointer to void named vptr, has been set to point to a floating point variable named g. What is the valid way to dereference vptr to assign its pointed value to a float variable named f later in this program?

float g;
void *vptr=&g;

• f = _(float _)vptr;
• f = (float *)vptr;
• f = *(float *)vptr;
• f = *(float)vptr;

Q6. What is this declaration an example of?

struct s {
    int i;
    struct s *s1;
    struct s *s2;
};

• a node
• a linked list
• a stack
• a binary tree

Q7. A C header file is a file with extension .h that contains function declarations and macro definitons to be shared between several source files. Header files are listed using the preprocessing directive #include, and can have one of the following formats: #include <fileA> or #include "fileB". What is the difference between these two formats?

• The preprocessor will try to locate the fileA in same directory as the source file, and the fileB in a predetermined directory path.
• The preprocessor will try to locate the fileA in the fixed system directory. It will try to locate fileB in the directory path designated by the -l option added to the command line while compiling the source code.
• The file using fileA syntax must be system files, of unlimited number. fileB must be a user file at a maximun of one per source file.
• The preprocessor will try to locate the fileA in a predetermined directory path. It will try to locate fileB in the same directory as the source file along with a custom directory path.

Q8. Using a for loop, how could you write a C code to count down from 10 to 1 and display each number on its own line?

• [ ]

for (int i = 0; i>=0, i--){
    printf("%d\n", i);
}//end of loop

• [ ]

int i;
for (i=1; i<=10; i++){
    printf("%d", i);
}

• [ ]

int i = 10;
while (i>0){
    printf("%d\n", i);
    i--;
}

• [x]

int i;
for (i= 10; i>0; i--){
    printf("%d\n", i);
}// end of loop

Q9. What is not one of the reserved words in standard C?

• volatile
• typeof
• register
• typedef

Reference

Q10. What does the program shown below return?

int main(){
    int a=1, b=2, c=3, d=4;
    int x = a;
    if (a>b)
    if (b<c) x=b;
    else x=c;
    return(x);
}

• 1
• 3
• 2
• 0

Q11. Using the Union declaration below, how many bytes of memory space will the data of this type occupy?

union Cars {
    char make[20];
    char model[30];
    short year;
} car;

• 32
• 54
• 30
• 52

Q12. In this code sample, what is not a problem for C compiler?

main(){
    constant int PI = 3.14;
    printf("%f\n", pi);
}

• The value of PI needs to be set to 3.141593, not 3.14
• The declaration of PI needs to say const, not constant.
• The data type of PI needs to be float not int.
• The printf statement needs to use PI, not pi.

Q13. Which is the smallest program to compile and run without errors?

• main()
• int main() {return 0;}
• main() { }
• main() { ; }

Reference

Q14. What is optional in a function declaration?

• data type of parameters
• return type of function
• parameter names
• number of parameters

Q15. C treats all devices, such as the display and the keyboard, as files. Which files opens automatically when a program executes?

• stdout
• stdio.h
• default.h
• string.h

Q16. In which segment does dynamic memory allocation takes place?

• BSS Segment
• stack
• heap
• data segment

Reference

Q17. Which of the following do you use to deallocate memory?

• dalloc()
• dealloc()
• release()
• free()

Reference

Q18. In C language what are the basic building blocks that are constructed together to write a program?

• keywords
• identifiers
• tokens
• functions

Q19. When is memory for a variable allocated?

• during the assigment of the variable
• during the initialization of the variable
• during the declaration of the variable
• during the definition of the variable

Q20. By default c uses the call by value method to pass arguments to functions. How can you invoke the call by reference method?

• by using pointers
• by declaring functions separately from defining them
• by using recursive functions
• by using global variables

Q21. A union allows you to store different ___ in the same ___.

• Objects; Structure
• Variables; Declaration
• Data types; Memory location
• Arrays; Header file

Q22. What is the output of this program?

main() {
    char c1='a' , c2='A';
    int i=c2-c1;
    printf("%d", i);
}

• 32
• Runtime error
• -32
• 0

Q23. What is the difference between scanf() and sscanf() functions?

• The scanf() function reads data formatted as a string; The sscanf() function reads string input from the screen.
• The scanf() function reads formatted data from the keyboard; The sscanf() function reads formatted input from a string.
• The scanf() function reads string data from the keyboard; The sscanf() function reads string data from a string.
• The scanf() function reads formatted data from a file; The sscanf() function reads input from a selected string

Q24. What is not a valid command with this declaration?

char *string[20] = { "one", "two", "three"};

• printf("%c", string[1][2]);
• printf("%s", string[1][2]);
• printf("%s", string[1]);
• printf(string[1]);

Q25. What is the expression player->name equivalent to?

• player.name
• (*player).name
• *player.name
• player.*name

Q26. Which program will compile and run without errors?

• [ ]

main() {
    for(i=0; i<10; i++) ;
}

• [x]

main() {
int i=0;
    for(; i<10; i++) ;
}

• [ ]

main() {
    int i;
    for(i=0; i<j; i++) ;
}

• [ ]

main() {
int i;
    for (i= 10; i<10; i++)
}

Q27. What does this function call return?

1 main() { float x = f1(10, 5); }
2 float f1(int a, int b) { return (a/b); }

• 2
• 2.000000
• a runtime error
• a compiler error

Q28. What does this program create?

#include <stdio.h>
int main() {
    int *p = NULL;
    return 0;
}

• a runtime error
• a NULL pointer
• a compile error
• a void pointer

Q29. What is an alternative way to write the expression (*x).y?

• There is no equivalent.
• x->y
• *x->y
• y->x

Q30. Compile time errors are static errors that can be found where in the code?

• in declarations and definitions
• in functions and expressions
• in syntax and semantics
• in objects and statements

Q31. File input and output (I/O) in C is heavily based on the way it is done ___?

• in Unix
• in C++
• in C#
• in DOS

Q32. What does the strcmp(str1, str2); function return?

• 0 if str1 and str2 are the same, a negative number if str1 is less than str2, a positive number if str1 is greater than str2
• true (1) if str1 and str2 are the same, false (0) if str1 and str2 are not the same
• true (1) if str1 and str2 are the same, NULL if str1 and str2 are not the same
• 0 if str1 and str2 are the same, a negative number if str2 is less than str1, a positive number if str2 is greater than str1

Q33. What is the output of this program?

int a=10, b=20;
int f1(a) { return(a*b); }
main() {
printf("%d", f1(5));
}

• 100
• 200
• 5
• 50

Q34. Which is not a correct way to declare a string variable?

• char *string = "Hello World";
• char string = "Hello World";
• char string[20] = {'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd'};
• char string[] = "Hello World";

Q35. Which choice is an include guard for the header file mylib.h?

• [ ]

#ifdef MYLIB_H
#undef MYLIB_H

// mylib.h content

#endif /* MYLIB_H */

• [x]

#ifndef MYLIB_H
#define MYLIB_H

// mylib.h content

#endif /* MYLIB_H */

• [ ]

#define MYLIB_H
#include "mylib.h"

#undef MYLIB_H

• [ ]

#ifdef MYLIB_H
#define MYLIB_H

// mylib.h content

#endif /* MYLIB_H */

Q36. How many times does the code inside the while loop get executed in this program?

main(){
 int x=1;
 while(x++<100){
    x*=x;
    if(x<10) continue;
    if(x>50) break
 }
}

• 100
• 3
• 5
• 50

Q37. File input and output (I/O) in C is done through what?

• syntax-driven components
• native interfaces
• system objects
• function calls

Q38. Directives are translated by the?

• Pre-processor
• Compiler
• Linker
• Editor