C Cheat Sheet

#include <stdio.h>int main(void) {    int age = 30;    double pi = 3.14159;    char name[] = "Ada";    if (age >= 18) {        printf("%s is an adult\n", name);    }    for (int i = 0; i < 5; i++) {        printf("Count: %d\n", i);    }    return 0;}

int x = 42;int *p = &x;        // p holds address of x*p = 100;            // dereference: x is now 100int arr[5] = {1, 2, 3, 4, 5};int *ptr = arr;      // array decays to pointerprintf("%d\n", *(ptr + 2));  // 3, same as arr[2]void swap(int *a, int *b) {    int temp = *a;    *a = *b;    *b = temp;}

#include <stdlib.h>int *arr = malloc(5 * sizeof(int));  // allocate on heapif (arr == NULL) {                   // always check for failure    return 1;}arr[0] = 10;arr = realloc(arr, 10 * sizeof(int)); // grow the blockfree(arr);                            // release memoryarr = NULL;                           // avoid dangling pointer