Let’s de-obfuscate it. Indenting: main(_) { _^448 && main(-~_); putchar(–_%64 ? 32 | -~7[__TIME__-_/8%8][“>’txiZ^(~z?”-48] >> “;;;====~$::199″[_*2&8|_/64]/(_&2?1:8)%8&1 : 10); } Introducing variables to untangle this mess: main(int i) { if(i^448) main(-~i); if(–i % 64) { char a = -~7[__TIME__-i/8%8][“>’txiZ^(~z?”-48]; char b = a >> “;;;====~$::199″[i*2&8|i/64]/(i&2?1:8)%8; putchar(32 | (b & 1)); } else { putchar(10); // newline … Read more
In the Old Days (pre-ANSI), predefining symbols such as unix and vax was a way to allow code to detect at compile time what system it was being compiled for. There was no official language standard back then (beyond the reference material at the back of the first edition of K&R), and C code of … Read more
++i will increment the value of i, and then return the incremented value. i = 1; j = ++i; (i is 2, j is 2) i++ will increment the value of i, but return the original value that i held before being incremented. i = 1; j = i++; (i is 2, j is 1) … Read more
Unless that value is 0 (in which case you can omit some part of the initializer and the corresponding elements will be initialized to 0), there’s no easy way. Don’t overlook the obvious solution, though: int myArray[10] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 }; Elements with missing values will … Read more
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 … Read more
Executive summary: int a[17]; size_t n = sizeof(a)/sizeof(a[0]); Full answer: To determine the size of your array in bytes, you can use the sizeof operator: int a[17]; size_t n = sizeof(a); On my computer, ints are 4 bytes long, so n is 68. To determine the number of elements in the array, we can divide … Read more
A static variable inside a function keeps its value between invocations. A static global variable or a function is “seen” only in the file it’s declared in (1) is the more foreign topic if you’re a newbie, so here’s an example: #include <stdio.h> void foo() { int a = 10; static int sa = 10; … Read more
Function pointers in C Let’s start with a basic function which we will be pointing to: int addInt(int n, int m) { return n+m; } First thing, let’s define a pointer to a function which receives 2 ints and returns an int: int (*functionPtr)(int,int); Now we can safely point to our function: functionPtr = &addInt; … Read more
The C standard defines the [] operator as follows: a[b] == *(a + b) Therefore a[5] will evaluate to: *(a + 5) and 5[a] will evaluate to: *(5 + a) a is a pointer to the first element of the array. a[5] is the value that’s 5 elements further from a, which is the same … Read more
This is, in effect, a way to check whether the expression e can be evaluated to be 0, and if not, to fail the build. The macro is somewhat misnamed; it should be something more like BUILD_BUG_OR_ZERO, rather than …ON_ZERO. (There have been occasional discussions about whether this is a confusing name.) You should read … Read more