Why Doesn't `ifstream::open()` Work with `std::string` Arguments?

No matching function for ifstream open()

The issue arises in the code snippet:

std::ifstream file;
file.open(name); // the error is here

Dev C encounters errors "no matching function for call 'std::basic_ifstream::open(std::string&)" and "no matching function for call 'std::basic_ofstream::open(std::string&)". These errors occur because the open() function in ifstream expects a C-style string as an argument, but the code provides a std::string.

Solution:

To resolve this issue, convert the std::string to a C-style string using the c_str() member function:

file.open(name.c_str());

Alternatively, you can directly initialize the ifstream object with the C-style string:

std::ifstream file(name.c_str());

In addition, consider declaring loadNumbersFromFile() as follows:

std::vector<int> loadNumbersFromFile(const std::string& name)

This change indicates that the function does not modify its argument and prevents an unnecessary copy.

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