Tag Archives: text file

Java || Snippet – How To Read & Write Data From A File

This page will consist of a demonstration of a simple quadratic formula program, which highlights the use of the input/output mechanisms of manipulating a text file. This program will read in data from a file (numbers), manipulate that data, and output new data into a different text file.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Try/Catch - What Is It?
The "Math" Class - sqrt and pow
The "Scanner" Class - Used for the input file
The "FileWriter" Class - Used for the output file
The "File" Class - Used to locate the input/output files
Working With Files

NOTE: The data file that is used in this example can be downloaded here.

In order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .java file is saved in. If you are using Eclipse, the default directory will probably be:


Documents > Workspace > [Your project name]

Alternatively, you can execute this command, which will give you the current directory in which your source file resides:


System.out.println(System.getProperty("user.dir"));

Whatever the case, in order to read in the data .txt file, your program must know where it is located on the system.


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output
(Remember to include the example input file)

Welcome to My Programming Notes' Java Program.

For the numbers:
a = 2.0
b = 4.0
c = -16.0

root 1 = 2.0
root 2 = -4.0

Program Success!!

C++ || Snippet – How To Read & Write Data From A User Specified Text File

This page will consist of a demonstration of a simple quadratic formula program, which highlights the use of the input/output mechanisms of manipulating a text file. This program is very similar to an earlier snippet which was presented on this site, but in this example, the user has the option of choosing which file they want to manipulate. This program also demonstrates how to read in data from a file (numbers), manipulate that data, and output new data into a different text file.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Fstream
Ifstream
Ofstream
Working With Files
C_str() - Convert A String To Char Array Equivalent
Getline - String Version

Note: The data file that is used in this example can be downloaded here.

Also, in order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio 2010 > Projects > [Your project name] > [Your project name]


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

Please enter the name of the file: INPUT_Quadratic_programmingnotes_freeweq_com.txt

For the numbers
a = 2
b = 4
c = -16

root 1 = 2
root 2 = -4

Press ENTER to continue...

C++ || Class & Input/Output – Display The Contents Of A User Specified Text File To The Screen

The following is another intermediate homework assignment which was presented in a C++ programming course. This program was assigned to introduce more practice using the class data structure, which is very similar to the struct data structure.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Header Files - How To Use Them
Class - What Is It?
How To Read Data From A File
String - Getline
Array - Cin.Getline
Strcpy - Copy Contents Of An Array
#Define

This program first prompts the user to input a file name. After it obtains a file name from the user, it then attempts to display the contents of the user specified file to the output screen. If the file could not be found, an error message appears. If the file is found, the program continues as normal. After the file contents finishes being displayed, a summary indicating the total number of lines which has been read is also shown to the screen.

This program was implemented into 3 different files (two .cpp files, and one header file .h). So the code for this program will be broken up into 3 sections, the main file (.cpp), the header file (.h), and the implementation of the functions within the header file (.cpp).

Note: The data file that is used in this example can be downloaded here.

Also, in order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio 2010 > Projects > [Your project name] > [Your project name]

======== FILE #1 – Main.cpp ========

======== FILE #2 – CFileDisp.h ========

Remember, you need to name the header file the same as the #include from the Main.cpp file. This file contains the function declarations, but no implementation of those functions takes place here.

======== FILE #3 – CFileDisp.cpp ========

This is the function implementation file for the CFileDisp.h class. This file can be named anything you wish as long as you #include “CFileDisp.h”


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

C++ || Snippet – How To Read & Write Data From A File

This page will consist of a demonstration of a simple quadratic formula program, which highlights the use of the input/output mechanisms of manipulating a text file. This program will read in data from a file (numbers), manipulate that data, and output new data into a different text file.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Fstream
Ifstream
Ofstream
Working With Files

NOTE: The data file that is used in this example can be downloaded here.

Also, in order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio > Projects > [Your project name] > [Your project name]


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

For the numbers
a = 2
b = 4
c = -16

root 1 = 2
root 2 = -4

C++ || Input/Output – Using An Array, Sort Names From a Text File & Save The Sorted Names To A New Text File

Since we previously discussed how to sort numbers which is contained in an integer array, it is only fitting that we display a program which sorts characters that are stored in a character array.

This is an interactive program which first displays a menu to the user, allowing them to choose from 6 different modes of operation. The 6 options are described as followed:

R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

From the available choices, the user has the option of reading in names from a file, manually entering in names themselves, displaying the current names in the array, sorting the current names in the array, clearing the current names in the array, and finally quitting the program. When the user chooses to quit the program, whatever data which is currently stored within the array will automatically be saved to the output text file.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Fstream
Ifstream
Ofstream
Character Arrays
2D Arrays
Working With Files
Pass By Reference
While Loops
For Loops
Bubble Sort
Functions
Switch Statements
Boolean Expressions
Toupper
Strcpy
Strcmp

The data file that is used in this example can be downloaded here.

Note: In order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio 2010 > Projects > [Your project name] > [Your project name]

NOTE: On some compilers, you may have to add #include < cstdlib> and #include < cstring> in order for the code to compile.


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output
(Remember to include the input file)

Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> d

The array is currently empty!

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> q

The array contained no names.
There was no data to save to the output file...

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> e

Please enter the number of names you want to sort: 3

Please enter 3 names

Name #1: My
Name #2: Programming
Name #3: Notes

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> d

The values in the array are:
My
Programming
Notes

There is currently 3 names in the array!

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> s

Sorting the names contained in the array...
Success!
------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> d

The values in the array are:
My
Notes
Programming

There is currently 3 names in the array!

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> c

Deleting the data contained in the array...
Clearing Complete!
------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> r

Reading in data from the file...
Success!
------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> d

The values in the array are:
My
Programming
Notes
C++
Java
Assembly
Lemon
Dark
Light
Black
High
Low
Cellphone
Cat
Dog
Penguin
Japan
Peace
Love
Color
White
One
Brain
Eggplant
Phalanx
Countenance
Crayons
Ben
Dover
Eileen
Bob
Downe
Justin
Elizebeth
Rick
Rolled
Sam
Widge
Liza
Destruction
Grove
Aardvark
Primal
Sushi
Victoria
Ostrich
Zebra
Scrumptious
Carbohydrate
Sulk
Ecstatic
Acrobat
Pneumonoultramicroscopicsilicovolcanoconiosis
English
Kenneth
Jessica
Pills
Pencil
Dragon
Mint
Chocolate
Temperature
Cheese
Rondo
Silicon
Scabbiest
Palpitate
Invariable
Henpecked
Titmouse
Canoodle
Boobies
Pressure
Density
Cards
Twiat
Tony
Pink
Green
Yellow
Duck
Dodge
Movie
Zoo
Xiomara
Eggs
Marshmallows
Umbrella
Apple
Panda
Brush
Handle
Door
Knob
Mask
Knife
Speaker
Wood
Orient
Love

There is currently 100 names in the array!

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> s

Sorting the names contained in the array...
Success!
------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> d

The values in the array are:
Aardvark
Acrobat
Apple
Assembly
Ben
Black
Bob
Boobies
Brain
Brush
C++
Canoodle
Carbohydrate
Cards
Cat
Cellphone
Cheese
Chocolate
Color
Countenance
Crayons
Dark
Density
Destruction
Dodge
Dog
Door
Dover
Downe
Dragon
Duck
Ecstatic
Eggplant
Eggs
Eileen
Elizebeth
English
Green
Grove
Handle
Henpecked
High
Invariable
Japan
Java
Jessica
Justin
Kenneth
Knife
Knob
Lemon
Light
Liza
Love
Love
Low
Marshmallows
Mask
Mint
Movie
My
Notes
One
Orient
Ostrich
Palpitate
Panda
Peace
Pencil
Penguin
Phalanx
Pills
Pink
Pneumonoultramicroscopicsilicovolcanoconiosis
Pressure
Primal
Programming
Rick
Rolled
Rondo
Sam
Scabbiest
Scrumptious
Silicon
Speaker
Sulk
Sushi
Temperature
Titmouse
Tony
Twiat
Umbrella
Victoria
White
Widge
Wood
Xiomara
Yellow
Zebra
Zoo

There is currently 100 names in the array!

------------------------------------------------------------
Welcome to the name sorting program...
From the following menu, select an option
R - Read in names from a file for sorting
E - Enter in names manually for sorting
D - Display the current names in the array
S - Sort the current names in the array
C - Clear the current names in the array
Q - Quit

>> q

Saving the current contents of the array to the ouptut file..
Success!

C++ || Input/Output – Find The Average of The Numbers Contained In a Text File Using an Array/Bubble Sort

This program highlights more practice using text files and arrays. This program is very similar to one which was previously discussed on this site, but unlike that program, this implementation omits the highest/lowest values which are found within the array via a sort.

The previously discussed program works almost as well as the current implementation, but where it fails is when the data which is being entered into the program contains multiple values of the same type. For example, using the previously discussed method to obtain the average by omitting the highest/lowest entries found within an array, if the array contained the numbers:

1, 2, 3, 3, 3, 2, 2, 1

The previous implementation would mark 1 as being the lowest number (which is correct) and it would mark 3 as being the highest number (which is also correct). The area where it fails is when it omits the highest and lowest scores found within the array. The program will skip over ALL of the numbers contained within the array which equal to 1 and 3, thus resulting in the program obtaining the wrong answer.

To illustrate, before the previous program computes its adjusted average scores, it will not only omit just 1 and 3 from the array, but it will also omit all of the 1’s and 3’s from the list, resulting in our array looking like this:

2, 2, 2

When you are finding the average of a list of numbers by omitting the highest/lowest scores, you don’t want to omit ALL of the values which may equal said numbers, but merely just the highest (last element in the array) and lowest (first element in the array) scores.

So if the previous implementation has subtle issues, why is it on this site? The previous program illustrates very well the process of finding the highest/lowest integers found within an array. It also works flawlessly for data in which there is non repeating values found within a list (i.e 1,2,3,4,5,23,6). So if you know you are reading in from a file in which there are non repeating values, the previous implementation works well. Often times though, developers do not know what type of data the incoming files will contain, so this current implementation is a better way to go, especially if it is not known exactly how many numbers are contained within a file.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Fstream
Ifstream
Ofstream
Working With Files
While Loops
For Loops
Bubble Sort
Basic Math - Finding The Average

The data file that is used in this example can be downloaded here.

Note: In order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio 2010 > Projects > [Your project name] > [Your project name]

NOTE: On some compilers, you may have to add #include < cstdlib> in order for the code to compile.


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output
(Remember to include the input file)

The numbers countained in the input file are: 12, 45, 23, 46, 11, -5, 23, 33, 50, 17, 13, 25, 15, 50,
The highest and lowest numbers contained in the file are:
Highest: 50
Lowest: -5

The average of the 14 numbers contained in the file is: 25.5714
The average of the 14 numbers contained in the file omitting the highest and lowest scores is: 26.0833

C++ || Input/Output Text File Manipulation – Find Highest, Lowest, Average & Total Sum

This is a program which will utilize fstream, specifically ifstream and ofstream, to read in data from one .txt file, and it will then output selected data into an entirely new separate .txt file.

The input data file has 8 different rows, with each row containing 7 numbers on each line. The program will take in each line one at a time, manipulating the 7 numbers to receive the desired output. This program will find the highest/lowest number in each selected line, along with the total sum of all the numbers contained in that line, and the average of all the numbers. So at the end of the program, There will be 8 different sets of data compiled for each row, with the output file looking like this:

SAMPLE RUN:

- Input File -
3 5 7 3 4 5 6

- Output File -
The dataset for input line #1 is: 3 5 7 3 4 5 6
The highest number is: 7
The lowest number is: 3
The total of the numbers is: 33
The average of the numbers is: 4.71

The data file that is used in this example can be downloaded here

Note: In order to read in the data .txt file, you need to save the .txt file in the same directory (or folder) as your .cpp file is saved in. If you are using Visual C++, this directory will be located in

Documents > Visual Studio > Projects > [Your project name] > [Your project name]

NOTE: On some compilers, you may have to add #include < cstdlib> in order for the code to compile.


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

LOOPS
This program utilizes one do/while loop on lines 39-97 which loops thru the input file until it reaches the end of the file. This program also uses a for loop, which is noted on line 46.

CALCULATING THE SUM
Line 50 contains the assignment operator “+=“, which will calculate a running total for all the values of each selected line.

READING IN DATA FROM FILE
This is noted in line 48, and works just like a cin statement.

OPENING FILES
File declarations, and the opening of files are highlighted on lines: 14-15, 24-25, 32-33. On line 32, the term “ios::app” means the file will append new data to the text file, instead of overwriting the old data contained within that file.

OUTPUT DATA TO FILE
This is highlighted on lines 80-84, and as you can see, the output statements are exactly the same as cout statements.

CLOSE FILES
Remember to close the files you open, as highlighted on lines 101 and 102.

Once compiling the above code, you should receive this as your output (for the 8 selected lines contained within the input text file)

The dataset for input line #1 is: 346 130 982 90 656 117 595
The highest number is: 982
The lowest number is: 90
The total of the numbers is: 2916
The average of the numbers is: 416.571

The dataset for input line #2 is: 415 948 126 4 558 571 87
The highest number is: 948
The lowest number is: 4
The total of the numbers is: 2709
The average of the numbers is: 387

The dataset for input line #3 is: 42 360 412 721 463 47 119
The highest number is: 721
The lowest number is: 42
The total of the numbers is: 2164
The average of the numbers is: 309.143

The dataset for input line #4 is: 441 190 985 214 509 2 571
The highest number is: 985
The lowest number is: 2
The total of the numbers is: 2912
The average of the numbers is: 416

The dataset for input line #5 is: 77 81 681 651 995 93 74
The highest number is: 995
The lowest number is: 74
The total of the numbers is: 2652
The average of the numbers is: 378.857

The dataset for input line #6 is: 310 9 995 561 92 14 288
The highest number is: 995
The lowest number is: 9
The total of the numbers is: 2269
The average of the numbers is: 324.143

The dataset for input line #7 is: 466 664 892 8 766 34 639
The highest number is: 892
The lowest number is: 8
The total of the numbers is: 3469
The average of the numbers is: 495.571

The dataset for input line #8 is: 151 64 98 813 67 834 369
The highest number is: 834
The lowest number is: 64
The total of the numbers is: 2396
The average of the numbers is: 342.286

We have reached the end of the file!