Strings are hard work in C. The 12 is enough bytes to store the text “pre_”, the text “_suff”, a string of up to two characters (“99”) and the NULL terminator that goes on the end of C string buffers. This will tell you how to use snprintf, but I suggest a good C book!
You cannot use pEDGE within the definition of the struct. You shoud do something like: You must also note that edge_item is a double pointer. You also mention that in your question. So if you use pEDGE_ITEM and you just want to have a normal pointer you should not write pEDGE_ITEM *edge_item but just pEDGE_ITEM … Read more
S_ISREG() is a macro used to interpret the values in a stat-struct, as returned from the system call stat(). It evaluates to true if the argument(The st_mode member in struct stat) is a regular file. See man stat, man fstat or man inode (link to inode man page) for further details. Here’s the relevant part … Read more
By older versions of the POSIX standard the first method with an initializer is only guaranteed to work with statically allocated variables, not when the variable is an auto variable that is defined in a function body. Although I have never seen a platform where this would not be allowed, even for auto variables, and … Read more
You need to add #include <stdio.h> to the top of your file.
I’m doing a program that aproximate PI and i’m trying to use long long, but it isn’t working. Here is the code
switch labels must be constant expressions, they have to be evaluated at compile time. If you want to branch on run-time values, you must use an if. A const-qualified variable is not a constant expression, it is merely a value you are not allowed to modify. The form of integer constant expressions is detailed in … Read more
Internal implementation of strtok has already been discussed here: How does strtok() split the string into tokens in C? In your type of implementation ( calling it your type because it is quite different from the actual one), you have not allocated any memory dynamically to the local variable ‘W’. So when you return it, … Read more
There is already a question about copy_from_user, but it is a little bit too advanced for me, I want to see simple example of using the copy_from_user method within kernel module, what is the simplest example of using that method?
I’m beginner with C and I am learning on my own. I am creating the following function: I am basically trying to return an appended string, but I get the following error: “error: function returns address of local variable”, any suggestions, how to fix this?