How to Read Whole ASCII File into C++ std::string?

12 May 2025 | 2 min read

In this article, we will discuss how to read whole ASCII file into C++ std::string. Before going to its implementation, we must know about the ASCII file in C++.

What is the ASCII Files?

The ext files converted to ASCII format allow data to be imported into programs other than the source. Delimited formats and Fixed-width formats are the two most common formats. One of the delimited formats is a CSV (comma-separated value).

Use the std::ifstream class to access and read the file and the std::istreambuf_iterator to read all the contents of the file into a string, and we can read the entire ASCII file and store it in std::string.

Approach:

If we use the std::ifstream file(filePath), open the file first that opens the file and generates the input file stream to read from the given file.
Next, use the is_open() method to check if the file opened successfully. Return from the function, if the opening fails, print an error.
After that, use the std::istreambuf_iterator<char>(file) function to read the entire file into a string. It creates an iterator to read characters from the file from the beginning.
Close the file stream and print the filled string.