The part of the retina that gives sharp central vision — the macula — deteriorates, causing blind spots and blurred vision. Cataracts occur when proteins in the eye begin to build up and create a milky cloud over the lens. In the beginning stages of cataracts, vision may only be slightly blurry or hazy.
Over time, the cloudiness prevents light from reaching the retina, resulting in vision loss. Glaucoma is a disease that usually is tied to pressure inside the eyeball. Other cases of glaucoma result from a lack of blood flow to the optic nerve. Glaucoma is especially tricky because there are no symptoms until significant damage has been done to your peripheral vision.
In many cases, yes, bad eyesight can be genetic. Doctors at the Cleveland Clinic have found that the most common eye diseases for older adults like the ones listed above are inherited. Individuals with these markers are nearly 10 times more likely to have refractive errors than those without genetic influence. There are also environmental factors that influence the health of your eyes and vision. Excessive sun exposure without the protection of quality sunglasses has been known to lead to glaucoma and cataracts.
How to avoid this? Smoking is bad for your eyes. The New York State Department of Health warns that smokers are three to four times more likely to develop macular degeneration than non-smokers. How to improve your poor eyesight depends on the cause of your vision issues.
I remember this has something to do with stack protection and security, but I'm not sure exactly why. In order to use gets safely, you have to know exactly how many characters you will be reading, so that you can make your buffer large enough. You will only know that if you know exactly what data you will be reading. Instead of using gets , you want to use fgets , which has the signature. Most C implementations still support it, but at least gcc issues a warning for any code that uses it.
The first internet worm the Morris Internet Worm escaped about 30 years ago , and it used gets and a buffer overflow as one of its methods of propagating from system to system.
The basic problem is that the function doesn't know how big the buffer is, so it continues reading until it finds a newline or encounters EOF, and may overflow the bounds of the buffer it was given. Sadly, it will remain in libraries for many years meaning 'decades' for reasons of backwards compatibility. If it were up to me, the implementation of gets would become:.
Given that your code will crash anyway, sooner or later, it is better to head the trouble off sooner rather than later.
I'd be prepared to add an error message:. Modern versions of the Linux compilation system generates warnings if you link gets — and also for some other functions that also have security problems mktemp , ….
As everyone else said, the canonical alternative to gets is fgets specifying stdin as the file stream. What no-one else yet mentioned is that gets does not include the newline but fgets does. So, you might need to use a wrapper around fgets that deletes the newline:. Also, as caf points out in a comment and paxdiablo shows in his answer, with fgets you might have data left over on a line. My wrapper code leaves that data to be read next time; you can readily modify it to gobble the rest of the line of data if you prefer:.
The residual problem is how to report the three different result states — EOF or error, line read and not truncated, and partial line read but data was truncated. This problem doesn't arise with gets because it doesn't know where your buffer ends and merrily tramples beyond the end, wreaking havoc on your beautifully tended memory layout, often messing up the return stack a Stack Overflow if the buffer is allocated on the stack, or trampling over the control information if the buffer is dynamically allocated, or copying data over other precious global or module variables if the buffer is statically allocated.
There is also the TR Technical Report from the C Standard Committee which provides safer alternatives to a variety of functions, including gets :. A new-line character, end-of-file, or read error shall occur within reading n-1 characters from stdin. No additional characters are read after a new-line character which is discarded or after end-of-file. The discarded new-line character does not count towards number of characters read. A null character is written immediately after the last character read into the array.
In general this requires that callers of fgets pay attention to the presence or absence of a new-line character in the result array. Programs that use gets expect such a relationship. The Microsoft Visual Studio compilers implement an approximation to the TR standard, but there are differences between the signatures implemented by Microsoft and those in the TR. Unfortunately, it is seldom implemented on Unix-like systems.
POSIX also provides a safe alternative to gets called getline. It allocates space for the line dynamically, so you end up needing to free it. It removes the limitation on line length, therefore. It also returns the length of the data that was read, or -1 and not EOF!
Because gets doesn't do any kind of check while getting bytes from stdin and putting them somewhere. A simple example:. Now, first of all you are allowed to input how many characters you want, gets won't care about it. Secondly the bytes over the size of the array in which you put them in this case array1 will overwrite whatever they find in memory because gets will write them. In the previous example this means that if you input "abcdefghijklmnopqrts" maybe, unpredictably, it will overwrite also array2 or whatever.
You should not use gets since it has no way to stop a buffer overflow. If the user types in more data than can fit in your buffer, you will most likely end up with corruption or worse. In fact, ISO have actually taken the step of removing gets from the C standard as of C11, though it was deprecated in C99 which, given how highly they rate backward compatibility, should be an indication of how bad that function was.
The correct thing to do is to use the fgets function with the stdin file handle since you can limit the characters read from the user. To that end, almost every C coder at some point in their career will write a more useful wrapper around fgets as well. Here's mine:. It provides the same protections as fgets in that it prevents buffer overflows but it also notifies the caller as to what happened and clears out the excess characters so that they do not affect your next input operation.
If your dog is not a chewer and you do not regularly brush his teeth or have his teeth cleaned, then the most likely cause of his bad breath is plaque build-up. Over time, poor oral hygiene can lead to periodontal disease. Too much plaque and tartar build-up can push the gums away from the teeth, exposing new areas for bacteria to develop. Needless to say, it also leads to very, very bad breath. Unpleasant Dietary Habits Dogs can be gross.
Sometimes their habits translate directly into bad breath. If your dog regularly gets into the garbage, or has access to decomposing animal remains, then his bad breath could be the result of unsupervised snacking. Dogs also universally seem to love cat poop, and a household with cats can offer too much temptation for your dog to resist.
Not only is this smelly, it is also unhygienic. Sweet, fruity breath is a symptom of diabetes , a serious but treatable condition. Talk with your veterinarian about the other symptoms of diabetes to look out for, like more frequent drinking and urination, and set up an appointment to get your dog examined.
Kidney disease is serious and could be a symptom of a larger medical problem. Like kidney disease , liver problems can be a sign of a serious condition, and it is vital that you get your dog into the veterinarian or emergency clinic as soon as possible. Treating Bad Dog Breath As important as it is to understand the underlying issues behind malodorous doggie breath, what we really want to know is how to get rid of it.
Tooth Brushing Basics Did you know that having a regular tooth brushing routine can have a major impact on your dog's health? Download this e-book to learn more. AKC Privacy Policy.
0コメント