- C++ Basics
- Scherlokk 3 5 – Find And Compare Files Using Word
- Scherlokk 3 5 – Find And Compare Files Using Python
- Scherlokk 3 5 – Find And Compare Files Using Keyboard
- Scherlokk 3 5 – Find And Compare Files Using Excel
- Pre-copy hard linked files together (using find's '-type f -links +1' options) before running fpsync. That will work but linked files that have changed since your first synchronization will be converted back to regular files when running fpsync. Use a final -monolithic- rsync pass with option -H that will re-create them.
- Nirsoft HashMyFiles. HashMyFiles is another small and portable tool from Nir Sofer that is simple and straightforward to use. The number of ways to open files is impressive because you can add single or multiple files, folders (including sub folders), running processes, and also by wildcard with custom folder depth.
- Use spaces to separate multiple search strings unless the argument is prefixed with /c. To search for hello or there in file x.y, type: findstr hello there x.y To search for hello there in file x.y, type: findstr /c:'hello there' x.y To find all occurrences of the word Windows (with an initial capital letter W) in the file proposal.
- John Stanley continues his fine Rathbonian Holmes, and Wendell Holmes (credited as the generic 'George Spelvin' to avoid confusion with between his name and the name of the main character) takes over as an unassuming Watson: his voice acting is top-notch, but his character, lacking the quirks of previous interpretations of the role, becomes far too obviously a mere sounding board to draw out.
Smith and Stein Explain 5 Practices for Math Tasks.pdf.
- C++ Object Oriented
- C++ Advanced
- C++ Useful Resources
- Selected Reading
So far, we have been using the iostream standard library, which provides cin and cout methods for reading from standard input and writing to standard output respectively.
This tutorial will teach you how to read and write from a file. This requires another standard C++ library called fstream, which defines three new data types −
Sr.No | Data Type & Description |
---|---|
1 | ofstream This data type represents the output file stream and is used to create files and to write information to files. |
2 | ifstream This data type represents the input file stream and is used to read information from files. |
3 | fstream This data type represents the file stream generally, and has the capabilities of both ofstream and ifstream which means it can create files, write information to files, and read information from files. |
To perform file processing in C++, header files and must be included in your C++ source file.
Opening a File
A file must be opened before you can read from it or write to it. Either ofstream or fstream object may be used to open a file for writing. And ifstream object is used to open a file for reading purpose only.
Folder tidy 2 7 2. Following is the standard syntax for open() function, which is a member of fstream, ifstream, and ofstream objects.
Here, the first argument specifies the name and location of the file to be opened and the second argument of the open() member function defines the mode in which the file should be opened.
Sr.No | Mode Flag & Description |
---|---|
1 | ios::app Append mode. All output to that file to be appended to the end. |
2 | ios::ate Open a file for output and move the read/write control to the end of the file. |
3 | ios::in Open a file for reading. |
4 | ios::out Open a file for writing. |
5 | ios::trunc If the file already exists, its contents will be truncated before opening the file. |
You can combine two or more of these values by ORing them together. For example if you want to open a file in write mode and want to truncate it in case that already exists, following will be the syntax −
Similar way, you can open a file for reading and writing purpose as follows −
Closing a File
When a C++ program terminates it automatically flushes all the streams, release all the allocated memory and close all the opened files. But it is always a good practice that a programmer should close all the opened files before program termination.
Following is the standard syntax for close() function, which is a member of fstream, ifstream, and ofstream objects.
Writing to a File
While doing C++ programming, you write information to a file from your program using the stream insertion operator (<<) just as you use that operator to output information to the screen. The only difference is that you use an ofstream or fstream object instead of the cout object.
Reading from a File
You read information from a file into your program using the stream extraction operator (>>) just as you use that operator to input information from the keyboard. The only difference is that you use an ifstream or fstream object instead of the cin object.
Read and Write Example
Following is the C++ program which opens a file in reading and writing mode. After writing information entered by the user to a file named afile.dat, the program reads information from the file and outputs it onto the screen −
When the above code is compiled and executed, it produces the following sample input and output −
Above examples make use of additional functions from cin object, like getline() function to read the line from outside and ignore() function to ignore the extra characters left by previous read statement.
File Position Pointers
Both istream and ostream provide member functions for repositioning the file-position pointer. These member functions are seekg ('seek get') for istream and seekp ('seek put') for ostream.
The argument to seekg and seekp normally is a long integer. A second argument can be specified to indicate the seek direction. The seek direction can be ios::beg (the default) for positioning relative to the beginning of a stream, ios::cur for positioning relative to the current position in a stream or ios::end for positioning relative to the end of a stream.
The file-position pointer is an integer value that specifies the location in the file as a number of bytes from the file's starting location. Some examples of positioning the 'get' file-position pointer are −
Like many other programming languages, PowerShell has various comparison operators. However, unlike other languages, those comparison operators can look a little odd. Instead of , you have eq
. Instead of <>
, you've got ne
. It can be confusing to newcomers. Let's demystify PowerShell comparison operators in this article.
Testing for Equality With eq
and ceq
Operators
To check to see if one object is equal to another object in PowerShell is done using the eq
operator. The eq
operator compares simple objects of many types such as strings, boolean values, integers and so on. When used, the eq
operator will either return a boolean True
or False
value depending on the result.
The -eq
operator needs two values to compare. Let's say you assign a string to a variable called $string
. You'd like to compare this variable's value to the string value 'PowerShell'
to ensure they are equal.
In the following example, you can see that we're assigning the value PowerShell
to the variable $string
. Then, using the eq
operator, the example is comparing the value of $string
with the string powershell
. Easy enough, right? But wait, they aren't really the same though.
Note that =
is an assignment operator and NOT a comparison operator. You cannot use =
to compare one value against another in PowerShell.
Testing Case-Sensitivity With the ceq
Operator
In the above example, notice how eq
returned a boolean True
value above even when the string wasn't the exact same. This behavior happens because the eq
operator is case-insensitive. To test for case-sensitive equality, use the ceq
operator. The ceq
operator is the exact same as eq
with the exception of being case-sensitive.
You can see an example of using ceq
in the following code snippet. Now notice the PowerShell sees the case-sensitive difference.
Testing for Inequality With the ne
and cne
Operators
Just as eq
and ceq
test for equality, PowerShell has a pair of operators that do the exact opposite called ne
and cne
. Like their counterparts, these two operators perform the exact same operation yet opposite.
Testing for Items in a Collection
Typically, the eq
and ceq
operators are used for scalar or single values like strings, integers and boolean values. But these operators can also find instances of particular values contained within a collection like an array.
Notice in the example below that we're creating an array with 12 integers. Perhaps you'd like to find all instances in that array that equal the number 9. No problem, use the eq
operator against the array to return all instances of the compared integer.
Testing Collections to Contain Values
Since you just learned about using the eq
operator to find instances in arrays, let's take that a step further and introduce the 'containment' operators. These operators are contains
, notcontains
, in
and notin
. These operators return a boolean True
or False
value if a collection contains an instance or not.
Check out the following example. In this example, we're creating an array with nine integers. If you want a simple Yes/No answer to if that array contains a certain integer, you can get that using contains
or notcontains
.
Similarly, you have the in
and notin
operators. These operators are nearly identical to contains
and notcontains
with one exception: the value to compare is on the left instead of the right.
Testing 'Greater than' With gt
and ge
Operators
What happens if you need to test whether a number (an integer) is greater than another number or perhaps greater than or equal to another number? You'd use the gt
and ge
operators. These operators compare integers.
Like the other operators, these operators return boolean True
or False
values depending on if one integer is greater than another. Both of these operators test whether the left integer is greater than or greater than or equal to the right integer.
In the below example, you can see how each of these operators behave.
Similar to the eq
operator that allows you to find instances in collections, you can do the same with the ge
and gt
operators too. PowerShell searches through each item in a collection and compares each value to the one you've provided. You can see a great example of this below.
Testing 'less than' With lt
and le
Operators
Similar to the gt
and ge
operators, the lt
and le
operators perform the same function yet opposite. The lt
and le
operators compare two values testing whether the integer on the left side is less than or less than or equal to the integer on the right.
You can see in the example below, the same functionality of comparing each value in a collection applies exactly the same as gt
and ge
.
Matching Based on Wildcards
So far, you've learned how to perform 1:1 matches. All of the operators used so far compared one whole value against another but PowerShell has another trick up it's sleeve. You can also compare values based on wildcards or asterisks.
Let's say you only know a few characters of a string. You can't use eq
because eq
requires you to know the entire string. Using the like
operator, you don't have to know the entire string. To test if a value is like another, you can replace the part you don't know with a wildcard.
As with other operators, this same functionality can be applied to collections too.
You can see an example of like
and it's case-sensitive brother, clike
below.
The operator -notlike
returns boolean True
if no match found and False
if there is a match. In case of using against a collection, it will return all other values that don't match the pattern given on the right side of the -notlike
operator. Adding case sensitivity to the pattern, use -cnotlike
operator.
Matching Based on Regular Expression
The like
operator and its relative are handy but as soon as you begin to require more complex matching. At that point, you can dive into the deep, dark world of regular expressions (regex). Using the match
and notmatch
operators, you can perform extremely complex string matching with regex.
Scherlokk 3 5 – Find And Compare Files Using Word
Like the other operators, match
and it's opposite counterpart, notmatch
, compares two strings return a boolean True
or False
value. Also, like the other operators, the same behavior can be applied for a collection as the example below demonstrates.
Scherlokk 3 5 – Find And Compare Files Using Python
Summary
In this article, you learned about PowerShell comparison operators and how to use each operator for single value and collections. You've seen how the output differs based on the operator and whether scalar or collection.
Scherlokk 3 5 – Find And Compare Files Using Keyboard
Additionally, you've also seen operators with case sensitivity, matching operators how to match based on regular expression or wildcard, and containment operators to test if the object contains a specific value or if a value is existing in a specific object.