The answer is right there in the man page (at least on Linux): RETURN VALUE The alloca() function returns a pointer to the beginning of the allocated space. If the allocation causes stack overflow, program behaviour is undefined. Which isn’t to say it should never be used. One of the OSS projects I work on … Read more
When you call malloc(), you specify the amount of memory to allocate. The amount of memory actually used is slightly more than this, and includes extra information that records (at least) how big the block is. You can’t (reliably) access that other information – and nor should you :-). When you call free(), it simply … Read more
Use the z modifier: size_t x = …; ssize_t y = …; printf(“%zu\n”, x); // prints as unsigned decimal printf(“%zx\n”, x); // prints as hex printf(“%zd\n”, y); // prints as signed decimal
int* arr[8]; // An array of int pointers. int (*arr)[8]; // A pointer to an array of integers The third one is same as the first. The general rule is operator precedence. It can get even much more complex as function pointers come into the picture.
(The approach of the better_enums library) There is a way to do enum to string in current C++ that looks like this: ENUM(Channel, char, Red = 1, Green, Blue) // “Same as”: // enum class Channel : char { Red = 1, Green, Blue }; Usage: Channel c = Channel::_from_string(“Green”); // Channel::Green (2) c._to_string(); // … Read more
Here is a real world example: Fixed point multiplies on old compilers. These don’t only come handy on devices without floating point, they shine when it comes to precision as they give you 32 bits of precision with a predictable error (float only has 23 bit and it’s harder to predict precision loss). i.e. uniform … Read more
For Linux the correct command is: gcc -pthread -o term term.c In general, libraries should follow sources and objects on command line, and -lpthread is not an “option”, it’s a library specification. On a system with only libpthread.a installed, gcc -lpthread … will fail to link.
Short story: The 0 tells the parser it’s dealing with a constant (and not an identifier/reserved word). Something is still needed to specify the number base: the x is an arbitrary choice. Long story: In the 60’s, the prevalent programming number systems were decimal and octal — mainframes had 12, 24 or 36 bits per … Read more
If you run without debugging (Ctrl+F5) then by default it prompts your to press return to close the window. If you want to use the debugger, you should put a breakpoint on the last line.
As Greg Hewgill said, the typedef means you no longer have to write struct all over the place. That not only saves keystrokes, it also can make the code cleaner since it provides a smidgen more abstraction. Stuff like typedef struct { int x, y; } Point; Point point_new(int x, int y) { Point a; … Read more