dmitry / learn-c Goto Github PK

Here are my notes for the C language, that I've made for a quick reference in the future. It something like a cheatsheet, but very personal.

int a[4] = {1,2,3,4};
int a[] = {1,2,3,4};
int a[] = {0};
int *pa;
int **pb;

take third element of an array

a[3] == *(a + 3) == 3[a] == *(&a[0] + 3) - basically array variable is a pointer on a first element of array

if (a[3] == *(a + 3) &&
  a[3] == 3[a] &&
  a[3] == *(&a[0] + 3)) {
  printf("yey");
}

*pa - get value

pa - get or set memory location

pa = a

pa = &a[0] - the same as above

*a - get first element of array

int &b - reference, cannot be NULL or uninitialized

pa = &b - get address of variable and assign it to pointer

**pb = &pa - reference on reference

#include <stdio.h>

int referenced(int val) {
  return 2 * val;
}

void execute(int (*ptr)(int)) {
  printf("%d\n", ptr(3));
}

int main() {
  int (*ptr_func)(int) = &referenced;

  execute(ptr_func);

  return 1;
}

• strace
• ltrace
• dtrace
• ktrace

• http://en.cppreference.com/w/