What is the function of inls open() in c++

The ifstream::open() function is used to open a file for reading. It takes a filename and an optional file opening mode as arguments. If the file is opened successfully, an ifstream object is associated with it. Available file opening modes include read-only, write, append, truncate, and binary modes, which can be combined.

##ifstream::open() function in C

##ifstream The ::open()

function is a member function of the ifstream class in the C standard library, which is used to open a file for reading.

Syntax:

<code class="cpp">void open(const char* filename, std::ios_base::openmode mode = std::ios_base::in);</code>

Parameters:

filename
• : The file to be opened name.
mode
• (optional): Specify the file opening mode. The default value is std::ios_base::in (read-only).

Return value:

None.

Function:

ifstream::open()

The function attempts to open the specified file for reading. After the file is successfully opened, the ifstream object is associated with the file.

Usage:

<code class="cpp">std::ifstream input_file;
input_file.open("input.txt");

if (input_file.is_open()) {
  // 文件已成功打开
} else {
  // 文件打开失败
}</code>

File opening mode:

mode

Parameters specify how to open the file . The following modes are available:

std::ios_base::in
• : read-only mode (default)
std::ios_base::out
• : Write mode (open or create)
std::ios_base::app
• : Append mode (open or create and append to the end of the file)
std::ios_base::trunc
• : Truncation mode (open or create and truncate file)
std::ios_base::binary
• : Binary mode
The modes can be combined using:

<code class="cpp">input_file.open("input.txt", std::ios_base::in | std::ios_base::binary);</code>

This will open the "input.txt" file in binary mode for reading.

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