Week 1

Question 1

What are the 7 fundamental features of C…?

Answer 1

Imperative : Focuses on how the program should achieve its goals.
Procedural : Program consists of a sequence of statements.
Compiled
Weak or Strong typed : Strong due to required type declaration, weak because accommodates type casting.
Statically typed : Types are checked before run time.
Portable : Compatibility on almost all modern machines. Is the native language of Unix.
Fast : Due to compiled nature and explicit memory management.

Question 2

What does ANSI stand for? What was the purpose of making C ANSI standard?

Answer 2

American National Standards Institute. To ensure that C was portable, reliable and maintainable.

Question 3

What does it mean that C has explicit memory management?

Answer 3

Programmers manually deal with memory management and garbage collection.

Question 4

Give 2 cons of using C?

Answer 4

Does not have run time error checking.
Does not have sophisticated exception handling.

Question 5

What is the process for compiling and linking C files?

Answer 5

1. Compile all the .c and .h files. This converts them to machine readable object files.
2. Link all the object files into one executable file.
3. Run the executable file.

Question 6

C is statically typed. What does this mean? What is the main advantage of this?

Answer 6

It means typing is checked at compile time. This provides protection from runtime errors.

Question 7

What is the difference between a runtime error and a compile time error?

Answer 7

Runtime errors are errors that are not picked up by the compiler, and occur during running of the program, which causes a crash.
Compile time errors are usually semantic or syntactic errors which the compiler picks up and highlights before running. E.g int a = “Hello world” would leave to a compile time error.

Question 8

What is the different between an initialised and un-initialised variable?

Answer 8

Un-initialised is declared but does not have any data assigned to it. Initialised is declared and has data assigned to it.

Question 9

Give me 9 data types C uses… What is the bite size and range of each?

Answer 9

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
float: 4 bytes
double: 8 bytes
long int: 8 bytes
long double: 16 bytes

Question 10

What method can be used to get the number of bytes of a data type? Which pre-processor directive is it in?

Answer 10

stddef.h
sizeof( float )

Question 11

Which pre-processor directive contains the symbolic constants that hold the maximum sizes of data types?

Answer 11

limits.h
CHAR_BIT -> Gives size of a character in bits
CHAR_MAX -> Gives max value of a char type etc.

Question 12

List all the conversion characters for scanf…

Answer 12

%d -> decimal integer
%f -> floating point number (float)
%s -> string
%c -> char
%lf -> floating point number (double)

Question 13

When printing, how would you write a print statement that outputs: * 5 *

Answer 13

printf(“%5d%5c”, x,’’);

Question 14

When printing floats, the width and decimal places can be specified. What would the expression %10.2f output?

Answer 14

A floating point number with a field with of 10, and to 2 decimal places.

Question 15

List all format specifies that can be used for printf…

Answer 15

%c -> character
%d -> decimal integer
%e -> floating point number in scientific notation
%f -> floating point number
%g -> use either e-format or f-formal, whichever is shorter
%s -> string

Question 16

How would you compile and link the files fileOne.c fileTwo.c into one executable called myProgram in 2 terminal commands?

Answer 16

gcc -c fileOne.c fileTwo.c
gcc fileOne.o fileTwo.o -o myProgram

Question 17

Talk through the process of compiling and linking using GNU compiler gcc

Answer 17

Run gcc, which checks the source code tokens for semantic or syntactic errors.
Upon succesful compilation, object files for each source file is created.
The object files can then be linked using gcc into one executable file.

Question 18

What are the 6 tokens that the compiler analyses when checking the source code? If an issue is found, what happens?

Answer 18

constants, string constants, keywords, identifiers, operators, punctuation.
A compile time error is raised if an issue is found.

Question 19

When 3rd party libraries are being used, what adjustment should be taken in the compilation step?

Answer 19

Add command library expression to the end of the command line argument.

Question 20

How do the loader and compiler components differ within the compilation system?

Answer 20

The compiler analyses the source code, creates object code of each source file. The loader then links these filers into one executable program.