No, stdin is not “a memory address”. It’s an I/O stream, basically an operating-system level abstraction that allows data to be read (or written, in the case of stdout). You need to use the proper stream-oriented I/O functions to read from the stream. Of course you can read from RAM too, so it’s best to write your own … Read more
UPDATE 2017: In C++17 there is now an official way to list files of your file system: std::filesystem. There is an excellent answer from Shreevardhan below with this source code (This code may throw): Old Answer: In small and simple tasks I do not use boost, I use dirent.h. It is available as a standard header in UNIX, and … Read more
With CMake, it’s generally recommended to do an “out of source” build. Create your CMakeLists.txt in the root of your project. Then from the root of your project: And for Debug (again from the root of your project): Release / Debug will add the appropriate flags for your compiler. There are also RelWithDebInfo and MinSizeRel build configurations. You can modify/add to the flags by specifying a toolchain file in … Read more
In C89 standard, initializer list must be compile time constants expressions, hence the warnings. However in C99 it is supported. In C89, you can do:
They are completely equivalent when used with printf(). Personally, I prefer %d, it’s used more often (should I say “it’s the idiomatic conversion specifier for int“?). (One difference between %i and %d is that when used with scanf(), then %d always expects a decimal integer, whereas %i recognizes the 0 and 0x prefixes as octal and hexadecimal, but no sane programmer uses scanf() anyway so this should not be a concern.)
You can’t return arrays from functions in C. You also can’t (shouldn’t) do this: returned is created with automatic storage duration and references to it will become invalid once it leaves its declaring scope, i.e., when the function returns. You will need to dynamically allocate the memory inside of the function or fill a preallocated buffer … Read more
The short answer is that it has no impact on printf, and denotes use of float or double in scanf. For printf, arguments of type float are promoted to double so both %f and %lf are used for double. For scanf, you should use %f for float and %lf for double. More detail for the language lawyers among us below: There is no difference between %f and %lf in the printf family. The ISO C standard (all references within are from C11), section 7.21.6.1 The fprintf … Read more
This is illegal in C. Initializer lists must be constant compile time expressions. Do the following instead:
The interface. Like everyone else has said, stdin is a FILE * as defined by the standard c library. You can use some of the higher level interfaces like fread, fwrite, and fprintf. On the other hand, STDIN_FILENO is just a file descriptor (almost certainly 0). This uses a slight lower level interface through the … Read more
The modulo operator in C will give the remainder that is left over when one number is divided by another. For example, 23 % 4 will result in 3 since 23 is not evenly divisible by 4, and a remainder of 3 is left over. If you want to output whether or not a number … Read more