Activate/deactivate Wi-Fi on Lenovo B5400 under Ubuntu 14.04

Question

I'm new to C and I would like to know if it's possible to write into a string the character \n from the keyboard by using scanf() function.

The code that I'm using is this: (sorry for the Italian variables words)

void riempi_array_stringhe (char* stringhe[], int lunghezza_array)
{
    for (int i = 0; i < lunghezza_array; i++) {
        stringhe[i] = (char*) malloc(sizeof(char) * 100);
        printf("Insert a new string: ");
        scanf("%s", stringhe[i]);
    }
}

I tried type shift + enter, alt + enter, or to insert \n as input but not works at all.

Thanks in advance!

Solution 1

A dirty trick worked: I booted the machine in Windows and started the wifi from Fn+F5 combination; note that this works in windows only when HotKey Intergration Driver is installed from lenovo site.

The main question is: what if one gets the laptop w/o Windows, e.g. free dos or linux pre-installed?

Solution 2

You can turn off your wifi using iwconfig.
To do that open a terminal and type the following command:

iwconfig wlan0 down

That should turn off your wifi. To turn it on you can use:

iwconfig wlan0 up

You can also turn it on/off using the wireless settings menu. Go to system setings → network → wireless. There you can turn it on/off.

Comments

[tom]

Doubt it can be done, just use getchar() or getch()

[sinkmanu]

A little trick is save the string in a file and input it. e.g. python -c 'print "A\nB\nhi"' > foo and ./your program < foo

[Paul R]

...or even fgets

[cup]

scanf is an input function: not an output function. You can't write with an input function.

[Rishal]

just press enter

[Lorenzo Imperatrice]

This question has a curiosity purpose, so yes, I can even do it like you guys said (that is actually the best way because scanf is dangerous to use), but i was interested in doing this with scanf function.

[Lorenzo Imperatrice]

@cup didn't exactly understand what you mean with this

[Lorenzo Imperatrice]

@Rishaldevsingh if I just press enter I just say to the program that I finished to input the string.

[Rishal]

what happens when you put '\n' as input in console, is there any error or any kind of output you are able to see

[Lorenzo Imperatrice]

@Rishaldevsingh it just write \n in the string

[tadman]

Why do people insist on using scanf for everything under the sun? It's not always the best tool, and in fact is often the worst possible tool due to how it can and will wildly overfill buffers.

[Lorenzo Imperatrice]

@tadman As I said in a comment before, This question has a curiosity purpose. You're right! scanf is the worst.

[Lucian Sasu]

Thanks for your answer. When I press on the on/off button you highlighted in the last picture, the button remains on the off position. Any clue?

[M.Tarun]

please post the output of rfkill list all

[Lucian Sasu]

Added as later edit for the question.

[Lorenzo Imperatrice]

So the best way is to terminate the string input in a different way, and there is no char (or combination of chars) that can be inserted from keyboard that represent \n in an input right??

[Andriy Berestovskyy]

@LorenzoImperatrice user can input \n and we can manually substitute it to newline in our code, i.e.: scanf(..., str[i]); str_replace(str[i], "\\n", "\n"); Please note there is no strreplace() in C, so you should google for an example implementation...

[Lorenzo Imperatrice]

Thank you very much for the detailed explanation!

[Jonathan Leffler]

Note that the %[^EOF] scan set looks for any character except capital-E, capital-O, capital-F — it has nothing to do with EOF except the coincidence that the list of letters is the same. Also note that %[^EOF] will read newlines into the string; indeed, it will keep reading until it crashes, or encounters one of the letters, E, F, O, or it runs into EOF. It won't stop merely because you reach the end of a line.