L1- C

Question 1

Source code

Answer 1

What humans write in a high-level language.

Question 2

Machine code

Answer 2

Binary, which computers understand, which is a low-level language

Question 3

Compiler

Answer 3

A program that translates one language to another language. For this example, it’s converting c to machine language

Question 4

Terminal window/console

Answer 4

Command line interface where you only use your keyboard

Question 5

GUI -(gooey)

Answer 5

Graphical user interface which are the buttons and things that you click on

Question 6

code

What does this command line program for this CS50 class do?

Answer 6

Open/create a new file to write
Usage: code filename. fileExt
code hello.c

Question 7

make
What does this command line program for this CS50 class do?

Answer 7

Compiles the file
Usage: make filename
make hello.c

Creates the executable without the ext
hello

Question 8

Command: ./

Answer 8

Runs the executable
Usage: ./Executable filename
./hello

Question 9

Command line: $

Answer 9

Represents the prompt in the terminal window

Question 10

Command line: .

Answer 10

Current folder?

Question 11

Command line: ..

Answer 11

Parent folder (up one folder)

Question 12

Escape sequence

Answer 12

specially delimited text in a character or string literal that represents one or more other characters to the compiler. It allows a programmer to specify characters that are otherwise difficult or impossible to specify in a literal.

An escape sequence starts with a backslash () called the escape character and subsequent characters define the meaning of the escape sequence. For example, \n denotes a newline character.

The same or similar escape sequences are used in other, related languages such C, C++, C#, Java and PHP

Question 13

Libraries

Answer 13

Code someone else wrote that needs to be included to use the functions within the file.
Ex: #include <stdio.h>
Standard io.h - input/output for C</stdio.h>

Question 14

.h file

Answer 14

Header file that gives you access to the libraries (functions)
stdio.h

Question 15

String

Answer 15

Text
“This is a string.”

Question 16

Int

Answer 16

Integer
32 bit Real #
123
~4 billion positive # or ~2 billion negative

Question 17

Float

Answer 17

Floating point
32 bit Decimal
1.23
~4 billion positive # or ~2 billion negative

Question 18

Char

Answer 18

Character
Exactly one uppercase letter
‘A’

Question 19

Long

Answer 19

Integer
64 bit Real #
123
More than 4 billion positive/2 billion with negative

Question 20

Double

Answer 20

64 bit Decimal (Floating point)
1.23
More than 4 billion positive/2 billion with negative

Question 21

Clear command line

Answer 21

Ctrl+l

Question 22

Dissect:
compiler error: hello.c:5:7:error use of undeclared identifier

Answer 22

hello.c - file with the error
5 - line number
7 - character
error use of undeclared identifier - message that usually means your variable isn’t defined before it is being used

Question 23

Format codes to print variables in C
printf(“text to print,__\n”, variable)
String

Answer 23

%s

Question 24

Format codes to print variables in C
printf(“text to print,__\n”, variable)
char

Answer 24

%c

Question 25

Format codes to print variables in C
printf(“text to print,__\n”, variable)
Float

Answer 25

%f

Question 26

Format codes to print variables in C
printf(“text to print,__\n”, variable)
double

Answer 26

%f

Question 27

Format codes to print variables in C
printf(“text to print,__\n”, variable)
int

Answer 27

%i

Question 28

Format codes to print variables in C
printf(“text to print,__\n”, variable)
long

Answer 28

%li

Question 29

Flowchart: Oval

Answer 29

Terminator( start/ stop)

Question 30

Flowchart: rectangle

Answer 30

Processes (tasks/actions)

Question 31

Flowchart: diamond

Answer 31

Decisions (binary choices)

Question 32

while loop

Answer 32

Checks for a condition to be true, then loops until it’s false

while(){
…
}

Question 33

do while loop

Answer 33

Performs the action once, then checks for a condition to be true, and loops until it’s false

do{
…
}while()

Question 34

for loop

Answer 34

Initializes and declares a variable, then perform the action until the expression is true. After performing the action, variable is incremented, then expression is checked again and continues until the expression is true.

for (int i = 0; i<3; i++){
…
}

Question 35

Function prototype

Answer 35

Return value. function name. arguments.
void meow()
void bark(int i)

Void returns nothing

Return value. function name. parenthesis. arguments.

Question 36

Scope

Answer 36

Context and which variables exist.
Local only exists within the curly brackets immediately surrounding it
Global exist and is accessible through entire page

Question 37

CLI

Answer 37

Another name for command line interface

Question 38

Command line: cd

Answer 38

Change directory
cd directory path

Question 39

Command line: cp

Answer 39

Copy
cp * file to copy* * new file name*

Question 40

Command line: up arrow

Answer 40

Toggles through previous commands

Question 41

Command line: ls

Answer 41

List
Shows all files in the current folder

Question 42

Command line: mkdir

Answer 42

Make directory
mkdir * New folder name*

Question 43

Command line: ./* Partial file name*

Answer 43

Will auto complete a name if it exists

Question 44

Command line: mv

Answer 44

Move, which is actually rename
mv * original file* * New file name*

Question 45

Command line: rm

Answer 45

Remove file /delete
rm * file name*

Confirm with y/n

Question 46

Command line: rmdir

Answer 46

Remove directory deletes

Question 47

Magic number

Answer 47

A unique value with unexplained meaning or multiple occurrences which could (preferably) be replaced with a named constant

Question 48

Constant

Answer 48

A variable that cannot be changed while the program is running

Question 49

RAM

Answer 49

Random access memory- all data in computer is stored here

Question 50

Integer overflow

Answer 50

When you don’t have enough memory, the numbers will wrap around and could be mistaken for zero or negative numbers incorrectly

Ex: Three bits can only count to seven as 111, then when going to 8, it would be 1000. Since there’s only three bits, all you would see would be 000 and would not be correct or as expected

Question 51

Truncation

Answer 51

When parts of data is cut off.
Example: when dividing an integer by an integer, the fraction gets thrown away, so you would not be able to display the fractional piece as is without changing the data type or casting

Question 52

Type cast

Answer 52

Converting a data type to another data type
Exam for trying to divide integers would need tight casting to display the fractional part
int x, y;
float z=(float) x/(float) y;

Question 53

How to set the number of decimal places for a float value

Answer 53

%.6f
This shows exactly six decimal places

Question 54

Floating point imprecision

Answer 54

Since there are a finite number of bytes it is impossible to show all values in a floating point number without some sort of rounding at some point.