stdio.h is standard, but deprecated. Always prefer cstdio in C++. [n3290: C.3.1/1]: For compatibility with the Standard C library, the C++ standard library provides the 18 C headers (D.5), but their use is deprecated in C++. [n3290: D.5/3]: [ Example: The header <cstdlib> assuredly provides its declarations and definitions within the namespace std. It may … Read more
I am surprised that there is a problem, but it does seem to be a problem on Linux (I tested on Ubuntu 16.04 LTS running in a VMWare Fusion VM on my Mac) — but it was not a problem on my Mac running macOS 10.13.4 (High Sierra), and I wouldn’t expect it to be … Read more
macOS I had this problem too (encountered through Macports compilers). Previous versions of Xcode would let you install command line tools through xcode/Preferences, but xcode5 doesn’t give a command line tools option in the GUI, that so I assumed it was automatically included now. Try running this command: xcode-select –install If you see an error … Read more
Unfortunately, HANDLEs are completely different beasts from FILE*s and file descriptors. The CRT ultimately handles files in terms of HANDLEs and associates those HANDLEs to a file descriptor. Those file descriptors in turn backs the structure pointer by FILE*. Fortunately, there is a section on this MSDN page that describes functions that “provide a way … Read more
All modern terminal emulators use ANSI escape codes to show colours and other things. Don’t bother with libraries, the code is really simple. More info is here. Example in C: #include <stdio.h> #define ANSI_COLOR_RED “\x1b[31m” #define ANSI_COLOR_GREEN “\x1b[32m” #define ANSI_COLOR_YELLOW “\x1b[33m” #define ANSI_COLOR_BLUE “\x1b[34m” #define ANSI_COLOR_MAGENTA “\x1b[35m” #define ANSI_COLOR_CYAN “\x1b[36m” #define ANSI_COLOR_RESET “\x1b[0m” int main … Read more
When a variable is defined, the compiler allocates memory for that variable. int i; // The compiler will allocate sizeof(int) bytes for i i defined above is not initialized and have indeterminate value. To write data to that memory location allocated for i, you need to specify the address of the variable. The statement scanf(“%d”, … Read more
Read each line, and use a random number to choose whether to keep that line or ignore it. For the first line, you want odds of 1:1 to keep; for the second, you want odds of 1:2, etc. count = 0; while (fgets(line, length, stream) != NULL) { count++; if ((rand() * count) / RAND_MAX … Read more
To answer the original question: Anything that can be done using stdio can be done using the iostream library. Disadvantages of iostreams: verbose Advantages of iostreams: easy to extend for new non POD types. The step forward the C++ made over C was type safety. iostreams was designed to be explicitly type safe. Thus assignment … Read more
char * fgets ( char * str, int num, FILE * stream ); is safe to use because it avoid buffer overflow problem, it scans only num-1 number of char. Reads characters from stream and stores them as a C string into str until (num-1) characters have been read or either a newline or the … Read more
Here’s the GNU version of printf… you can see it passing in stdout to vfprintf: __printf (const char *format, …) { va_list arg; int done; va_start (arg, format); done = vfprintf (stdout, format, arg); va_end (arg); return done; } See here. Here’s a link to vfprintf… all the formatting ‘magic’ happens here. The only thing … Read more