/*
    hello.c
	Jeff Ondich, 26 April 2019
    Part of a quick intro to C

	At a terminal with the gcc compiler
	installed, you can compile this program
	like so:

       gcc -o hello hello.c

	and then just run it with:

	   ./hello

    I generally include the "./" in this
    command line to avoid the problem where I
    accidentally name my program the same thing
    as a system program, and then run the system
    program instead. "./hello" says "run the
    command hello that's contained in the current
    directory."
*/
#include <stdio.h>

int main() {
    printf("Hello, world.\n");

    // There are several types of integers. Printing them with
    // printf looks like this. Note the correspondence between
    // the types and the %-codes.
    int a = 5;
    unsigned int b = 6;
    long c = 7;
    unsigned long d = 8;
    printf("a=%d, b=%u, c=%ld, d=%lu\n", a, b, c, d);

    // Printing in hexadecimal
    a = 165;
    printf("a in hexadecimal = %x\n", a);

    // The char type represents a single byte. So a char can hold
    // any ASCII character, but it can't hold any character with
    // codepoint above 255.
    char ch = 'Q';
    printf("ch = %c\n", ch);

    // Floating point types.
    float x = 3.1415926;
    double y = 2.718281828;
    printf("x = %f, y = %lf\n", x, y);
    printf("x with 4 digits past the decimal point = %.4f\n", x);

    // Why return 0? Because that tells most
    // Unix command shells that the program completed
    // without error.
    return 0;
}