C

// C cheat-sheet
#include <stdio.h>      // for printf, scanf
#include <string.h>     // for strlen, strcmp
#include <stdlib.h>     // for malloc, free

int main(void) {
    int x = 42;
    float pi = 3.14f;
    char c = 'A';
    char name[] = "ada";

    printf("Hello, %s!\n", name);   // %d int, %f float, %s string, %c char
    printf("x = %d\n", x);

    // Conditions
    if (x > 0) printf("positive\n");
    else if (x == 0) printf("zero\n");
    else printf("negative\n");

    // Loops
    for (int i = 0; i < 5; i++) printf("%d\n", i);

    int n;
    scanf("%d", &n);     // read an int (note the &)

    return 0;
}

// Functions
int add(int a, int b) {
    return a + b;
}

// Arrays
int nums[5] = {1, 2, 3, 4, 5};

// Pointers
int v = 10;
int *p = &v;     // p holds address of v
*p = 20;         // dereference: now v == 20

// Dynamic allocation
int *arr = (int*) malloc(10 * sizeof(int));
free(arr);