When you write the statement the compiler sees the constant string “abcdefghijklmnop” like an array. Imagine you had written the following code instead: Now, it’s a bit clearer what is going on. The left-hand side, *src, refers to a char (since src is of type pointer-to-char) whereas the right-hand side, otherstring, refers to a pointer. This isn’t strictly forbidden because you may want … Read more
The difference here is that will place “Hello world” in the read-only parts of the memory, and making s a pointer to that makes any writing operation on this memory illegal. While doing: puts the literal string in read-only memory and copies the string to newly allocated memory on the stack. Thus making legal.
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 (fgets, if it reads … Read more
In this case a[4] is the 5th integer in the array a, ap is a pointer to integer, so you are assigning an integer to a pointer and that’s the warning.So ap now holds 45 and when you try to de-reference it (by doing *ap) you are trying to access a memory at address 45, which is an invalid address, so your program crashes. You should do ap … Read more
fopen_s is a “secure” variant of fopen with a few extra options for the mode string and a different method for returning the stream pointer and the error code. It was invented by Microsoft and made its way into the C Standard: it is documented in annex K.3.5.2.2 of the most recent draft of the C11 Standard. Of course it … Read more
Try this: valgrind –leak-check=full -v ./your_program As long as valgrind is installed it will go through your program and tell you what’s wrong. It can give you pointers and approximate places where your leaks may be found. If you’re segfault’ing, try running it through gdb.
Note: Don’t use rand() for security. If you need a cryptographically secure number, see this answer instead.
In general, when “Bad File Descriptor” is encountered, it means that the socket file descriptor you passed into the API is not valid, which has multiple possible reasons: The fd is already closed somewhere. The fd has a wrong value, which is inconsistent with the value obtained from socket() api
Best to do the init’ing at declaration time: Only the arrays need to be done that way, but it’s best to do them all the same way. Your alternative is