CODEWITHSUNDEEP
c++filevisual-c++initialization
Pooria
Pooria

Reputation: 2055

A way to read data out of a file at compile time to put it somewhere in application image files to initialize an array

considering visual C++ compiler, Lets say I've got a file with whatever extension and it contains 100 bytes of data which are exactly the data that I want to initialize an array of char data type with a length of 100 characters with, Now apparently one way is to read those data out of file by using I/O file classes or APIs at run-time but what I want to know is that, is there any way using directives or something to tell the compiler I want to put that data in a right place in my application image files at compile time and compiler should go read those data out of that file?

Upvotes: 1

Views: 3717

Answers (4)

Galik
Galik

Reputation: 48635

What I frequently use in testing for textual data is I create a std::istringstream object containing the text of the file to be read like this:

#include <string>
#include <fstream>
#include <sstream>

// raw string literal for easy pasting in
// of textual file data
std::istringstream internal_config(R"~(

# Config file

host: wibble.org
port: 7334
// etc....

)~");

// std::istream& can receive either an ifstream or an istringstream
void read_config(std::istream& is)
{
    std::string line;
    while(std::getline(is, line))
    {
        // do stuff
    }
}

int main(int argc, char* argv[])
{
    // did the user pass a filename to use?
    std::string filename;
    if(argc > 2 && std::string(argv[1]) == "--config")
        filename = argv[2];

    // if so try to use the file
    std::ifstream ifs;
    if(!filename.empty())
        ifs.open(filename);

    if(ifs.is_open())
        read_config(ifs);
    else
        read_config(internal_config); // file failed use internal config
}

Upvotes: 1

letronje
letronje

Reputation: 9148

  • Write a program that reads the 100 byte data file and generates as output, a file, with c++ code/syntax for declaring an array with the 100 bytes in the file.
  • Include this new generated file(inline) in your main c++ file.
  • Call the c++ compiler on the main c++ file.

Upvotes: 4

Hans Passant
Hans Passant

Reputation: 942257

You do this with a resource in a Windows program. Right-click the project, Add, Resource, Import. Give the custom resource type a name. Edit the resource ID, if necessary. Get a pointer to the resource data at runtime with FindResource and LoadResource.

Upvotes: 2

Dipstick
Dipstick

Reputation: 10129

#include "filename"

or am I missing something obvious?

Upvotes: 0

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