CODEWITHSUNDEEP
c
Varun shah
Varun shah

Reputation: 35

How to shutdown windows using c program , where user enters the time

i've been learning c , and i want to create a c program , all it should do is to shutdown the computer after a certain user entered time.

i know how to perform an immediate shut down , using this code :

#include<stdlib.h>
int main()
{
 system("C:\\WINDOWS\\System32\\shutdown /s /t 00");
 return 0;
}

i create the .exe file , and execute , it runs fine. but i don't know how to shutdown after some time that the user enters. i tried the # operator as :

#include<stdio.h>
#include<stdlib.h>
#define shutown(x) system("C:\\WINDOWS\\System32\\shutdown /s /t" #x);

int main()
{
  int t;
  printf("\n enter secs :");
  scanf("%d",t);
  shutdown(t);
}

but the program did not work. i've never actually used # operator , but did search on it , here :

https://msdn.microsoft.com/en-us/library/7e3a913x.aspx

http://www.complete-concrete-concise.com/programming/c/preprocessor-%E2%80%93-understanding-the-stringizing-operator

but , i'm still not sure if i'm using the operator correctly.

i'd also like to create a program , which would create a folder in windows with user entered name , but i was planning to use # operator , and i guess i'm doing something wrong.

please tell me where am i going wrong , and any other logic to perform the same tasks.

thanks a lot !

Upvotes: 3

Views: 179

Answers (2)

Piper McCorkle
Piper McCorkle

Reputation: 1084

In your #define statement, shutdown is spelled shutown (copy+paste error?).

To use a variable in a #define macro, just put the name of the variable. Example:

#define shutdown(x) system("C:\\WINDOWS\\System32\\shutdown /s /t" x);

but call any functions in the macro as if you were calling them elsewhere. It does not substitute x for the value of t, it substitutes it for the literal t. Therefore,

system("C:\\WINDOWS\\System32\\shutdown /s /t" t);

will not work. You will need to concatenate the two strings with something like strcat.

You will need to #include <string.h> to use strcat, but after you've done that here's a modified shutdown:

#define shutdown(x) system(strcat("C:\\WINDOWS\\System32\\shutdown /s /t ", x));

DISCLAIMER: I have not tested any of this code, it's just a general guide. There may be problems, but this is the gist of what will work. Treat it as psuedocode.

Upvotes: 0

mtijanic
mtijanic

Reputation: 2902

The # operator is a preprocessor operator, meaning it is all done at compile time. You cannot use the values from the user there. You actually end up with:

system("C:\\WINDOWS\\System32\\shutdown /s /t" "t");

Which is definitely not what you want.

You actually want to have a local string buffer to which you will print the value, using something like sprintf and then calling system(buffer);

This will do what you want:

int main()
{
  int t;
  char buffer[100];
  printf("\n enter secs :");
  scanf("%d",&t); // Note that you need &t here
  sprintf(buffer, "C:\\WINDOWS\\System32\\shutdown /s /t %d", t); 
  system(buffer);
}

Upvotes: 4

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