Thread: Terminating console input in C and C++

Hi, I was having this exercise where I had to write some input/output functions in C++ but call C functions to do the job and throw an exceptions if errors occurred.

So now I have to write to file using fprintf and I suppose I'll use scanf to get input from console

When I was reading file I used this simple code (don't know if it's the best way to go)

Code:

FILE* fp = open_file(filename, "r");

for (char ch = 0; fscanf(fp, "%c", &ch) != EOF;)
    printf("%c", ch);

I think than when I'm getting some random text from console I also have to work with chars coz I don't know if next thing I'm getting is char or float or anything else from the input

When I have to do something like this in C++ I would use something like this

Code:

for(std::string line; std::getline(std::cin, line);){
    if(line == "__STOP__") break;   // woud use some keyword to terminate input

    //do something with line for example write line to some file
}

Is there some smart way to do the above example without using some terminating string?

How can I read some long random texts from console using scanf("%c", &ch)?

Is there a way to trigger EOF while using code something like this

Code:

while(scanf("%c", &ch) != EOF){
//do something with char
}

Is there a way to trigger std::cin.eof() if I'm using std::getline(std::cin, line) or even std::cin >> ch //char ch;

Any help appreciated.

EDIT : Why is my code looking so ugly except the middle one? Same tags around all of them.

Yes. Redirect input from a file, or trigger it with CTRL + D or CTRL + Z.

By the way, it is usually better to compare the return value of scanf with the number of expected assignments rather than with EOF.

I am entering whole line and only in the end I'm pressing ctrl + z and it displays something like "^Z" in console. Only than I'm pressing enter and its not working the 1st time

That's normal. The end of file character must be the first character entered to trigger EOF.

About exceptions - it was my exercise to create C++ functions that throw exceptions in case C functions cant open the files or do something else wrong.

Then why are you playing with scanf() in that loop. Just get a single string and then print that string to the file.

I also don't understand why you want to "throw exceptions in case C functions cant open the files or do something else wrong.", just don't use these C functions, stick with C++ streams.


Edit: Also posted here. I'm done.
Jim