Engineering 150 Midterm Cheat Sheet

A Programming › C cheat sheet in English by sukablukagyat

CPP Cheat Sheet for ENGN 150 Midterm

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PRs

Basic Operators

+	Addition
-	Subtraction
*	Multiplication
/	Division
=	Assign to Variable/Set equal to
%	Modulus (Int repersentation of remainder)
++var	increase before evaluation
var++	increase after evaluation
condition ? result : alternative;	short form of if-like structure

Input/Output

Cin	cin >> number;
Cout	cout << "Enter an integer: ";

Legal C++ Identifiers (The Rules for Var Names)

- Consists of letters (A-Z, Upper and Lowercase)
- Digits (NO DECIMALS)
- Underscores
- No Special Characters or Spaces
- No C++ Keywords by itself
- Must be Unique within it's namespace
- Case Sensitive

Example Switch Case

switch (operation) {
	case 0:
		// Things

		break;
	case 1:
		// Things

		break;
	case 2:
                // Things

		break;
        default:
                // Things

                break;
}

Operation must be an Int, Char, or Boolean. Case: must reflect that datatype.

Example If Else

if ( conditional ) {
   // do something
}
else if ( another_conditional ) {
   // do something else
}
else {
   // do something as default
}

Example For Sentence

for ( init; test; command ) {
   // do something
}

"break;" and "continue;" identical effects.

Example Do While Sentence

do {
   //do something
} while (bool expression);

Pointers

int *ptr;	Pointer definition
ptr = &var1;	ptr set to address of var1
var2 = *ptr;	set var2 to value of var1

Struct Example

// Declare Structure
struct Order {
    int modelNumber; 
    string phone;     
    float cost; 
};

// Main Function, define the structure variable
int main( ) {
    Order item1;

    // Give values to structure variables
    item1.modelNumber = 10;
    item1.phone = "Samsung Galaxy S";
    item1.cost = 1099.99;
    // Display/Output structure members
    cout << "Order, " << item1.phone << item1.modelNumber;
    cout << "This item costs: $" << part1.cost << endl;
}

// Output:
// Order, Samsung Galaxy S10
// This item costs: $1099.99

Boolean Logic

==	Test of Equality
!=	Test of Non-Equality
<	Less Than
>	Greater Than
<=	Less Than or Equal
>=	Greater Than or Equal
!	NOT
&&	AND
\|\|	OR

Boolean expressions in C++ are evaluated left-to-right!

Data Types

int	3
float	3.0f
double	3.0
char	'a'
string	"Hello World!"
bool	true/false

File Input / Output

#include <fstream.h>

ifstream file; //read buffer
ofstream file; //write buffer

file.open ("filename", [file mode constant]);

 //Test if the file was created 
if(fs.is_open())     if(fs)

//Reads/Writes like cin and cout
file >> var; //Read
file << ''Text: "<< var << endl; //Write

//Read Entire line
getline (file,String); 

//Read until it arrives at the end of file
while(file.eof())

//Detect if the read/write fail
if(file.fail())

//Close File
file.close();

Procedures

 //Declaration
 void ProcedureName()
{
   // do something
}

//Call to procedure
ProcedureName();

In the procedures we don't receive variables and don't return other variable.

Functions

//Declaration
 [returnType] functionName ( [input1Type input1Name, input2Type input2Name, ....] ) 
{
   // do something
   return value; // value must be of type returnType
}

//Call to function
[returntype var =] functionName ([input1Type input1Name, input2Type input2Name, ....])

We have two methods to create and call functions:
passed with values and passed for reference.

Pass by reference: we put & before variable in the declaration.
ReturnType must be a Datatype
Cannot return more than one thing

Dynamic Array Template

dataType *nameOfTheDynamicArray;

nameOfTheDynamicArray = new dataType[numofelements];

nameOfTheDynamicArray[0] = value;

delete [] nameOfTheDynamicArray;

"new" function allows dynamic array to change it size, since they are parameters.

"delete" will delete everything stored in the dynamic array.

enum example

enum gasType {gas, diesel};

gasType gasT;

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