Using extern is only of relevance when the program you’re building consists of multiple source files linked together, where some of the variables defined, for example, in source file file1.c need to be referenced in other source files, such as file2.c. It is important to understand the difference between defining a variable and declaring a variable: A variable is declared when the compiler is informed that a … Read more
Read it backwards (as driven by Clockwise/Spiral Rule): int* – pointer to int int const * – pointer to const int int * const – const pointer to int int const * const – const pointer to const int Now the first const can be on either side of the type so: const int * == int const * const int * const == int const … Read more
You must use %ld to print a long int, and %lld to print a long long int. Note that only long long int is guaranteed to be large enough to store the result of that calculation (or, indeed, the input values you’re using). You will also need to ensure that you use your compiler in a C99-compatible mode (for example, using the -std=gnu99 option to … Read more
http://lloyd.github.com/yajl/ http://www.digip.org/jansson/ Don’t really know how they compare for speed, but the first one looks like the right idea for scaling to really big JSON data, since it parses only a small chunk at a time so they don’t need to hold all the data in memory at once (This can be faster or slower … Read more
The compiler cannot tell from that code if the function will ever reach the end and still return something. To make that clear, replace the last else if(…) with just else.
What is the difference between the functions read() and pread() in unix?When choosing between them, what points should I take into consideration? I googled for the difference between them but without results.
If I transfer 1381530 bytes in 17797601 nanoseconds, what is the data rate in those two measures? 0.0776 bytes/ns. First, careful: I’ve recently discovered that MB/s is technically equivalent to 8000 million bits/s I’ve never heard of this definition. “MB/s” usually means “megabytes per second”. This can be one of two definitions, depending on who you ask: 1 … Read more
EDIT: As pointed out in the comment, itoa() is not a standard, so better use sprintf() approach suggested in the rivaling answer! You can use itoa() function to convert your integer value to a string. Here is an example: If you want to output your structure into a file there is no need to convert any value beforehand. You can just use … Read more
use the pow function (it takes floats/doubles though). man pow: EDIT: For the special case of positive integer powers of 2, you can use bit shifting: (1 << x) will equal 2 to the power x. There are some potential gotchas with this, but generally, it would be correct.
You need a double variable to store the result. int stores only integers. Additionally, you have to typecast the other variables also before performing the division. Do something like this NOTE: You do not need the & in printf() statements.