Introduction

General structure of a c++ program:

//Program 1.1

#include <iostream>
using namespace std;

int main()
{
	cout << "Welcome to C++\n";

    system("pause"); // to pause the console, so that it will not auto close after executing
	return 0;
}

Pseudocode and flowchart

Example of pseudocode:

Algorithm 2.1: To calculate the total of three numbers
1. Start
2. Set TOTAL to 0
3. Read NUMBER1
4. Read NUMBER2
5. Read NUMBER3
6. Add NUMBER1, NUMBER2 and NUMBER3 and store in TOTAL
7. Display TOTAL
8. End

Symbols of flowchart:

C language

Data types:

int id=109;
char symbol='$';
float average = 4.5;
long population = 4567890;
double volume = 6788.987;

Type casting (Change variable from one type to another, i.e. int variable to float variable):

// Program 4.2

int a=4, b=5, c;
double x=8.486,y=7.312,z;

z=a/b;
z=static_cast<double>(a)/b;
z = static_cast<double>(a/b);
c=static_cast<int>(x)/a;
c=static_cast<int>(x/a);
c=static_cast<int>(x)/static_cast<int>(y);

Input & Output

Screen input & output

// cout, cin
#include <iostream>
using namespace std;

int main ()
{
	float sales1, sales;
    cout << "Input two sales information." << endl;
    cout << "sales 1: ";
    cin >> sales1;
    cout << "sales 2: ";
    cin >> sales2;
    cout << "Total sales: " << (sales1+sales2);
    system("pause");
    return 0;
}

File input & output

// include fstream, ifstream, .open()
#include <iostream>
#include <fstream>
using namespace std;

int main ()
{
	float val1, val2, val3, val4;
    ifstream inData;
    ofstream outData;
    
    inData.open("DataIn.txt");
    outData.open("DataOut.txt");
    
    inData >> val1 >> val2 >> val3 >> val4;
    outData << val4 << endl;
    outData << val3 << endl;
    outData << val2 << endl;
    outData << val1 << endl;
    system("pause");
    return 0;
}

Stream manipulator

setw(5) - will create 5 spaces to display at console, if the thing to be displayed is less than 5, it will move to the right.

left, right - will make the thing to be displayed to be left of right within setw() length

setprecision(number): significant number

setprecision(number) and fixed: decimal points

showpoint: show zeros to match setprecision

#include <iostrea>
#include <iomanip>
using namespace std;

int main ()
{
	double amount;
    char s[100];
    
    cout << "D:";
    cin >> amount;
    cout << setprecision(2);
    cout << amount << endl;
    cout << fixed;
    cout << amount << endl;
    
    cout << "S:";
    cin >> s;
    cout << setw(6) << s << "END" << endl;
    cout << left << setw(6) << s << "END" << endl;
    system("pause");
    return 0;
}

digits	s
4.5	saya

D	:	4	.		5
4	.	5
4	.	5	0
S	:	s	a	y	a
		s	a	y	a	E	N	D
s	a	y	a			E	N	D

d	s
77.7777	sayaLagi

D	:	7	7	.	7	7	7	7
7	8
7	7	.	7	8
S	:	s	a	y	a	L	a	g	i
s	a	y	a	L	a	g	i	E	N	D
s	a	y	a	L	a	g	i	E	N

Selection or decision

if, else if, else
switch

If, else flowchart

If, else if, else flowchart

// if, else if, else
#include <iostream>
using namespace std;

int main ()
{
	double mark;
    
    cout << "Enter your mark>>";
    cin >> mark;
    
    if (mark >= 75)
    	cout << "Your score: A" << endl;
    else if ((mark < 75) && (mark >= 60))
    	cout << "Your score: B" << endl;
    else if ((mark < 60) && (mark >= 45))
    	cout << "Your score: C" << endl;
    else if ((mark < 45) && (mark >= 30))
    	cout << "Your score: D" << endl;
    else if (mark < 30)
    	cout << "Your score: E" << endl;
    system("pause");
    return 0;
}

switch flowchart

// switch
#include <iostream>
using namespace std;

int main ()
{
	char label;
    
    cout << "Enter a label >>";
    cin >> label;
    
    switch(label)
    {
    	case 'R':
        	cout << "Red Dragon";
            break;
        case 'Y':
        	cout << "Yellow pages";
            break;
        case 'r':
        	cout << "Red Hat";
            break;
        case 'z':
        	cout << "Red Apple";
            break;
    }
    system("pause");
    return 0;
}

Difference between break and continue:

Break: will stop the loop

Continue: will continue the loop but just skipped current iteration

Looping

while loop

while (condition)
{     
    statement(s);
}

First, condition is evaluated if it is true, the statement(s) are executed, and then condition is evaluated again if it is false, the loop is exited

while loop flowchart

int val = 5;
while (val >= 0)
{   cout << val << endl;
    val -= 1;
}
 /* output
 5
 4
 3
 2
 1
 0
 */

Use while loop for input validation

#include <iostream>
using namespace std;
int main()
{   
    int data, sum=0;
    cin >> data;

    while (data != 0)
    {     sum += data;
          cin >> data;
    }

    cout<< "The sum: " << sum << endl;

    system("PAUSE");
    return 0;
}

do while loop

do
{     
    statement(s);
}
while (condition);

First, the loop is executed once, then only check condition, if it is true, the statement(s) are executed, and then condition is evaluated again if it is false, the loop is exited

do-while loop flowchart

int mark;

do
{
    cout << "Enter marks for test 1: ";
    cin >> mark;    
}
while((mark < 0) || (mark > 100));

cout << "Your mark for test 1 is " << mark << endl;

for loop

for(initialization; test; update)
{
    statement(s);
}

for loop steps

for loop flowchart

int sum = 0;

for (int num = 1; num <= 10; num++)
{
    sum += num;   
}

cout << "Sum of numbers 1 – 10 is " << sum << endl;

Sentinel value/ Counter

Sentinel value/ Counter is placed at condition of loop to determine when the loop will stop

int total = 0;

cout << "Enter points earned " << "(or -1 to quit): ";
cin  >> points;

while (points != -1) // -1 is the sentinel
{
   total += points;  
   cout << "Enter points earned: ";
   cin  >> points;
}

Nested loop

A nested loop is a loop inside the body of another loop. Inner loop goes through all its repetitions for each repetition of outer loop

int main()
int x, y;
for(x=1; x<=8; x+=2)
{
   for(y=x; y<=10; y+=3)
   {
     cout << "x = " << x << " y = " << y << endl;
   }
}

Breaking out of loop

Break: Can use break to terminate execution of a loop.

Continue: Can use continue to go to end of loop and prepare for next repetition

Function

Pass by value

when an argument is passed to a function, its value is copied into the parameter. Changes to the parameter in the function do not affect the value of the argument

Demo of passing by value

Demo of passing by value and it doesn't change the value of argument

Pass by reference

When a reference is passed to a function, its value changes if it changes in the function. Defined with ampersand(&).

void getDimensions(int&, int&);

Demo of passing by reference

Function prototype, header, body, and call

// the prototype must include the data type of each parameter inside its parentheses
// the header must include a declaration for each parameter in its ()
void evenOrOdd(int);  //prototype
void evenOrOdd(int num) //header
evenOrOdd(val);       //call

Misc

Static variable, once declared, it will remain the same throughout the program execution. Demo

Array

one dimensional array

int foo[]; // wrong, because the size of array is not defined

int foo[5]; // declare an array with 5 elements of type int, element still no value because not yet initialize

int foo[5] = {16, 2, 77, 40, 12071};  // initialize the array
int foo[] = {16, 2, 77, 40, 12071}; // this will work too, without specifying number of elements

int baz[5] = {}; // initialize the array with each element with value of 0

foo[2] = 75; // set the 3rd element of foo array to 75

/* 
This will initialize a score array with 4 elements of type double with 0.0 for each element.
*/
// size declaration of an array must be a constant;
const int ARRAY_SIZE = 4;

double score[ARRAY_SIZE];

for(int i=0; i<ARRAY_SIZE; i++)
{
    score[i] = 0.0;
}
/*
end of program
*/

char name1[] = "Shaun"; // Way 1 of storing a string to array
char name2[] = {'S','h','a','u','n','\0'}; // Way 2 of storing a string to array, this have to end with \0

/*
Parallel array - Two or more related arrays that contain related data, maybe array1 will add with array2 and sum is stored in array3
*/
float time[] = {7,10,5,4,8};
float speed[] = {12.5,11.0,22.5,20.8,50.0};
float distance[] = {time[0]*speed[0], time[1]*speed[1], time[2]*speed[2], time[3]*speed[3], time[4]*speed[4]};

for(int i=0; i<5; i++)
{
    cout << "Time: " << time[i] << ", " << "Speed: " << speed[i] << ", " << "Distance: " << distance[i] << endl;
}
/*
end of program
*/

multidimensional array

int jimmy[3][4]; // declare a two dimensional array of 3 per 4 elements of type int

int jimmy[3][4] = {{2,3,4,9},{7,9,2,1},{1,0,12,13};  // initialize the array
int jimmy[][4] = {{2,3,4,9},{7,9,2,1},{1,0,12,13}; // this will work too, without specifying number of elements for first dimension, second and following dimension must specify number of elements

int jimmy[3][4] = {}; // initialize the array with each element with value of 0

int jimmy[1][3] = 100; // set the 2nd row, 4th column element to 100

/*
use two for loops to print out the contents of two dimensional array
*/
for(int i=0; i<3; i++)
{
    for (int j=0; j<4; j++)
    {
        cout << jimmy[i][j] << endl;
    }
}
/*
end of program
*/

Passing array to function

showScores(tests); //To pass an array to a function, just use the array name:
    
// To define a function that takes an array parameter, use empty [] for array argument:
void showScores(int []); // function prototype
void showScores(int tests[]) // function header

// For > 1 dimensional array, function header must specify all the size of dimension except 1st dimension
void getRectSolid(short [][3][5]);

Demo

Array names in functions are like reference variables – changes made to array in a function are reflected in actual array in calling function

shaunlgs/scsj1013-utm-programming-technique-1