Week 1 - Basics

Question 1

Is C imperative or declarative?

Answer 1

Imperative

Question 2

What is the difference between imperative and declarative programming languages?

Answer 2

Imperative describes computation in terms of statements that change a program state, e.g. C.

Declarative describes computation in terms of what is should accomplish, e.g. SQL.

Question 3

Is C object-oriented or procedural/functional?

Answer 3

Procedural/functional

Question 4

Is C compiled or interpreted?

Answer 4

Compiled

Question 5

C is statically, weakly typed - what does this mean?

Answer 5

Statically typed - types are checked before runtime (must declare variables before you use them).

Weakly typed - supports implicit type conversions.

Question 6

How do you declare a comment in C?

Answer 6

/* this is a comment */

Question 7

What does it mean when the main() function returns 0?

Answer 7

Success - everything else normally means failure.

Question 8

What is the statement #include <stdio.h> called, what part is the header file, and what is it used for?</stdio.h>

Answer 8

A compiler directive - used for including a library (in this case I/O with stdio.h, which is the header file)

Question 9

What header file is needed for standard I/O (input/output)?

Answer 9

stdio.h

Question 10

What is the process of turning a .c file into an executable program?

Answer 10

Source (.c or .h) compiles to object (.o or .obj), which is linked to executable (.exe)

Question 11

What is the standard compile?

Answer 11

gcc -ansi -c myProgram.c -o myProgram.o
(note -ansi not necessarily required)

Question 12

What is the standard link?

Answer 12

gcc myProgram.o -o myProgram

Question 13

How can several object files be linked together?

Answer 13

gcc myProgram.o mySubroutines.o -o myProgram

Question 14

What do make and makefiles do?

Answer 14

Utility for building executables and libraries from source code (compiling). They define how to compile and link files to build an executable. They only regenerate intermediate files when necessary.

Question 15

What is the header file for using mathematical functions (e.g. sqrt)?

Answer 15

math.h

Question 16

What does linking/loading do?

Answer 16

Linking combines object files and libraries into a single executable file, so performs other tasks, such as generating symbol tables that map the program’s symbols to their addresses in memory. Loading loads the executable file into memory and prepares it for execution. It allocates memory for the program’s code, data, and stack. The loader also performs tasks such as resolving any dynamic links to shared libraries and initializing the program’s global variables.

Often invoked by GCC itself:
gcc circle.o radius.o -o circle -lm

Question 17

How do you include a library when linking/loading?

Answer 17

-l for a library, e.g. -lm for the maths library.

Question 18

How do you compile and link in one go?
Use two files circle.c and radius.c, with main() in circle.c which uses the maths library.

Answer 18

gcc circle.c radius.c -o circle -lm

Question 19

What are the basic non-decimal data types in C, their sizes, and their range?

Answer 19

Unsigned char - 1 byte -> 0 to 255
Char - 1 byte -> -128 to 127
Unsigned short int -> 2 bytes - 0 to 65,535
Short int - 2 bytes -> -32,768 to 32,767
Int - 4 bytes -> -2,147,483,648 to 2,147,483,647
Long int - 8 bytes -> +/- 9 x 10^18

Question 20

What are the decimal data types in C, their sizes, their smallest and largest values and their precision?

Answer 20

Float - largest value is +/- 3.4 x 10^38, smallest is +/- 3.4 x 10^-38, precision is 6 digits

Double - largest value is +/- 1.07 x 10^308, smallest is +/- 1.07 x 10^-308, precision is 15 digits

Long double - 16 bytes -> largest value is +/- 3.4 x 10^4932, smallest is +/- 3.4 x 10^-4932, precision is 18 digits

Question 21

What is the header file needed to include minimum and maximum values of data types?

Answer 21

limits.h

Question 22

What is the header file needed to include the function sizeof()?

Answer 22

stddef.h

Question 23

What is the null character in C?

Answer 23

nullCharacter = ‘\0’

Question 24

How would you print the char variable ‘myChar’?

Answer 24

printf(“%c”, myChar)

Question 25

How do you print an int stored in variable myInt in C?

Answer 25

printf(“%d”, myInt)

Question 26

How do you print a float/double/long double variable stored in f in C?

Answer 26

printf(“%f”, f)

Question 27

How do you write an if-then-else statement in C?

Answer 27

if (<condition>)
{</condition>

<statement>
}
else if (<condition>)
{
<statement>
}
else
{
<statement>
}
</statement></statement></condition></statement>

Question 28

There are no explicit boolean datatypes in ANSI C. What is done instead?

Answer 28

Conditions are evaluated to int values -> 0 is false, anything else is true.

Question 29

What do the symbols || and && mean?

Answer 29

‘or’ and ‘and’

Question 30

How do you write a for loop in C?

Answer 30

for (<initialisation>; <condition>; <increment>)
{...}</increment></condition></initialisation>

Question 31

In a for loop in C, what do break and continue do?

Answer 31

Break jumps to the first statement after the end of the loop.

Continue jumps to the start of the next iteration.

Question 32

How do you write a while and a do while loop in C, and what is the difference between them?

Answer 32

while (<condition>)
{...}</condition>

do
{…}
while (<condition>);</condition>

A do while loop always runs the loop once; a while loop only runs if the condition is initially met.