File Handling in C++
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File Handling concept in C++ language is used for store a data permanently in computer. Using file handling we can store our data in Secondary memory (Hard disk).
Why use File Handling in C++
Mar 30, 2013 Easy Programming - Beginner C Tutorial - Using Header Files (.h Files) (26) - Duration: 5:48. Nazmus Nasir 35,619 views. C Header files Header files are provided as part of the definition of the MQI, to help you write WebSphere® MQ application programs in the C language. These header files are. Apr 16, 2020 Catch2 is a multi-paradigm test framework for C. Which also supports Objective-C (and maybe C). It is primarily distributed as a single header file, although certain extensions may require additional headers. How to use it. This documentation comprises these three parts: Why do we need yet another C Test Framework? Tutorial - getting started. Jul 03, 2019 #include – Enclosing the header file name within angular brackets signifies that the header file is located in the standard folder of all other header files of C/C. Step – 3 After the code is written using your file with the.h extension, compile and run your program. So,in your case, you need to use the dev-c compiler and create separate object files; Then using the linker you link both the object files to create the final executable; If there are functions that exist in the.cpp files that you want to reference, you use the header files. The header files contain the function/class declarations.
- For permanet storage.
- The transfer of input - data or output - data from one computer to another can be easily done by using files.
For read and write from a file you need another standard C++ library called fstream, which defines three new data types:
Datatype | Description |
---|---|
ofstream | This is used to create a file and write data on files |
ifstream | This is used to read data from files |
fstream | This is used to both read and write data from/to files |
![Header Header](/uploads/1/2/5/7/125700271/294725040.png)
How to achieve File Handling
For achieving file handling in C++ we need follow following steps
- Naming a file
- Opening a file
- Reading data from file
- Writing data into file
- Closing a file
Functions use in File Handling
Function | Operation |
---|---|
open() | To create a file |
close() | To close an existing file |
get() | Read a single character from a file |
put() | write a single character in file. |
read() | Read data from file |
write() | Write data into file. |
Defining and Opening a File
The function open() can be used to open multiple files that use the same stream object.
Example
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Closing a File
A file must be close after completion of all operation related to file. For closing file we need close() function.
File Opening mode
Mode | Meaning | Purpose |
---|---|---|
ios :: out | Write | Open the file for write only. |
ios :: in | read | Open the file for read only. |
ios :: app | Appending | Open the file for appending data to end-of-file. |
ios :: ate | Appending | take us to the end of the file when it is opened. |
Both ios :: app and ios :: ate take us to the end of the file when it is opened. The difference between the two parameters is that the ios :: app allows us to add data to the end of file only, while ios :: ate mode permits us to add data or to modify the existing data any where in the file.
The mode can combine two or more parameters using the bitwise OR operator (symbol |)
Example
File pointer
Each file have two associated pointers known as the file pointers. One of them is called the input pointer (or get pointer) and the other is called the output pointer (or put pointer). The input pointer is used for reading the contents of a given file location and the output pointer is used for writing to a given file location.
Function for manipulation of file pointer
When we want to move file pointer to desired position then use these function for manage the file pointers.
Function | Operation |
---|---|
seekg() | moves get pointer (input) to a specified location. |
seekp() | moves put pointer (output) to a specified location. |
tellg() | gives the current position of the get pointer. |
tellp() | gives the current position of the put pointer. |
fout . seekg(0, ios :: beg) | go to start |
fout . seekg(0, ios :: cur) | stay at current position |
fout . seekg(0, ios :: end) | go to the end of file |
fout . seekg(m, ios :: beg) | move to m+1 byte in the file |
fout . seekg(m, ios :: cur) | go forward by m bytes from the current position |
fout . seekg(-m, ios :: cur) | go backward by m bytes from the current position |
fout . seekg(-m, ios :: end) | go backward by m bytes from the end |
put() and get() function
The function put() write a single character to the associated stream. Similarly, the function get() reads a single character from the associated stream.
read() and write() function
These function take two arguments. The first is the address of the variable V , and the second is the length of that variable in bytes. The address of variable must be cast to type char * (i.e pointer to character type).
Read and Write data from/to File
File handling in C++
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