using /dev/urandom multiple times

I want to get a value from /dev/urandom and use the value, then assign a new value from /dev/urandom to the same variable and use that new value. This will be done in an if inside a while-loop that will keep repeting

I have tried using:

Code:

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fp = fopen("/dev/random", "r");
fclose(fp);

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and freopen() as well, but neither work

I end up with something like this:

Code:

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fp = fopen("/dev/random", "r");
value = (int)fp;
printf("%d", value); //if this prints 25
fclose(fp);

fp = fopen("/dev/random", "r");
value = (int)fp;
printf("%d", value); //then this prints 25
fclose(fp);

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I want the second value to be completly different, and also random

Why are you doing this:

Code:

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value = (int)fp;

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You're taking the value of the file pointer itself, not anything in the file. You're basically doing this:

Code:

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int *foo;
int bar = (int) foo;
bar = (int) foo;
bar = (int) foo;

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And wondering why they're all the same value.


Quzah.

And since I am using a pointer do I use fscanf to get data instead?

Quote:

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Originally Posted by miutsu

And since I am using a pointer do I use fscanf to get data instead?

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Actually I realy want a description of how to get these values since I plan on using them in a program to provide randomness

Cprogramming.com FAQ > Work with files (C)

Read the FAQ on working with files. Or the section of your book that covers it.


Quzah.

I think you need to use fread(). man page fread section 3

Quote:

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Originally Posted by Bayint Naung

I think you need to use fread(). man page fread section 3

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Thank you, that worked
I used:

Code:

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fp = fopen("/dev/urandom", "r");
fread(&random, sizeof(int), 1, fp);
random = abs(random);

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and it worked perfectly, but I dont have any man pages on fread or any other C functions, do you know where I could download those, I have Ubuntu.