Introduction to C

Question 1

What is C?

Answer 1

C is a weakly, statically-typed compiled language

Question 2

Define statically typed:

Answer 2

Variable types are known at compile time

Question 3

Define weakly-typed:

Answer 3

Relaxed approach to typing, for example variables can be implicitly converted to a different type

Question 4

Define compiled language:

Answer 4

Build assembly code and run it

Question 5

Is C Object Oriented Programming?

Answer 5

NO!

Question 6

How is memory management handled in C?

Answer 6

Memory management is handled by the programmer. Memory space must be managed and monitored.

Question 7

What is a preprocessor?

Answer 7

Passes through the code first and makes a number of substitutions with the directives pointed at (find and replace)

Question 8

What are the parameters of the main function?

Answer 8

1. int argc (Number of program arguments)
2. char* argv[] (array of program arguments)

Question 9

What is a declaration of definition of a variable?

Answer 9

Announcing its properties (type) and setting aside memory, but does not initialise it.

Question 10

What happens if a variable is not explicitly set?

Answer 10

Whatever was last stored in that memory space will be stored in that variable, until redefined.

Question 11

Can variables be redeclared in the local scope if the are defined in the global scope?

Answer 11

Variables can be redeclared in the local scope if it’s already defined in the global scope.

Question 12

Can variables be redefined in the global scope?

Answer 12

It cannot be redefined in the global scope if it already exists in there.

Question 13

What should we set used variables to after we don’t need them?

Answer 13

It is good practise to set the variables to 0/null after they’ve been used as there is no garbage collection in C unlike Java.

Question 14

In C what is static (in the global scope)?

Answer 14

A static in the global scope is a variable or function that is for the private use of functions in the declaring file only

Question 15

In C what is static (in the local scope)?

Answer 15

In the local scope a static variable is not destroyed at the end of the scope, the next time the scope is called, the previously set value will be there

Question 16

Is there a Boolean value in C?

Answer 16

No, 0 is true and any other number is false.

Question 17

What is void and what is its size?

Answer 17

Type for functions that take/return nothing. No size

Question 18

What are the common integer types and their size?

Answer 18

• char (8-bit)
• short (16-bit)
• int (32-bit)
• long (64-bit)
• unsigned char (8-bit)
• unsigned short (16-bit)
• unsigned int (32-bit)
• unsigned long (64-bit)

Question 19

What are the floating point types and their size?

Answer 19

• float (32-bit), works for most things
• double (64-bit), useful for accurate computation

Question 20

Where do we declare the iterator i for loops in C?

Answer 20

We must declare int i outside the loop. But initialisation can be done inside the loop.

Question 21

What is forward declaration?

Answer 21

Declaring the function exists before it is defined, as a form of function prototype.

Question 22

What do header files store?

Answer 22

Stores all the constants, macros, system wide global variables and function prototypes for the program.

Question 23

What is the compilation process in C?

Answer 23

1.Source Code, turned into expanded code by the pre-processor
2. Compiler compiles the code into assembly code
3. Assembler turns the assembly code into object code
4. Linker turns the object code into binary executable.

Question 24

What are the two main stages of compilation?

Answer 24

Compiling
- Compile each source/implementation file (.c) int object files (.o)

Linking
-Link all individual object files into one large binary executable

Question 25

Does code ordering matter in C?

Answer 25

Yes, if something is called before it is defined it will lead to compile errors

Question 26

Are header files compiled?

Answer 26

Header files are never directly compiled, the are only included to provide necessary information to compile.

Question 27

What is the syntax to include header files?

Answer 27

include “filename.h”

Question 28

What are header guards?

Answer 28

Header guards are pre-processor directives. Used to check if a header has been already been imported in the file.

Question 29

What are the three pre-processor directives for header guards?

Answer 29

1. If “EXAMPLE_H” is no defined:
   #ifndef EXAMPLE_H
2. Define “EXAMPLE_H”:
   #define “EXAMPLE_H”
3. End if:
   #endif