Untitled

#include <stdio.h> // Include me - library of input / output functions
# include <math.h> // Include me - library of mathematical functions



// This is how you comment in C


// Functions!

// In C, we use functions defined by what they return.

int square(int p) { // You put the functions above the main.
	return p * p;
}

// We can also have procedures. Procedures don't return a value!


void moo() {
	printf("moo");
}


int main() { // Always need a main!

	printf("This is how you type!\n");
	printf("Hello World\n"); // Put a new line at the end of every print!



	/* Note that the code that actually runs is always in the Source Files.
	 *This is how you do a multi-line comment btw.*/



	 // Unlike Python, you need to tell C what your variable is. For example...

	int x; // define a variable named x of type int
	x = 2;

	// You can define variables more efficiently also:

	int y = 5;
	int z = (0);



	// You can concatenate words!
	printf("%s%s", "Hello ", "Turtles!\n"); // Use of "%s%s" tells the computer were connecting two strings together.



	// We can also take user inputs.



	// First define a space for it:

	char name[50]; // This is a 49 character buffer. (Last character for null terminator, indicating end of string)

	printf("Enter your name\n");

	scanf_s("%49s", name, 50); // Feeding in 49 letters (%49). Any more and we get an overflow error. The 50 tells us the name was 50 long

	printf("Your name is %s\n", name);



	// Printing numbers

	int a = 0, b = 1, c = 2, d = 3, e = 4;
	a = b - c + d * e;
	printf("%d\n", a); // Will print 11. %d means a decimal number!



	/* For Boolean variables (True or False), we can use
	* ints. 0 for false, 1 for true! */



	// We can also make arrays!

	int myList[3];
	myList[0] = 10;
	myList[1] = 20;
	myList[2] = 30;

	printf("The second number in the array is %d\n", myList[1]);



	// We can also make 2D arrays!

	int twoDArray[3][4] = {
	 {0, 1, 2, 3} ,   /*  initializers for row indexed by 0 */
	 {4, 5, 6, 7} ,   /*  initializers for row indexed by 1 */
	 {8, 9, 10, 11}   /*  initializers for row indexed by 2 */
	};

	printf("The third number in second row of array is %d\n", twoDArray[1][2]);



	// Say you want an array to be all zeros...

	int zeroArray[10] = { 0 };


	// And yes, we can do IF statements!

	int foo = 1;
	int bar = 2;

	if (foo < bar) {
		printf("foo is smaller than bar.\n");
	}
	else if (foo == bar) {
		printf("foo is equal to bar.\n");
	}
	else {
		printf("foo is greater than bar.\n");
	}



	// Operators - AND, OR, NOT

	// AND = &&
	// OR = ||
	// NOT = !



	// DIVISION

	// Integer division: int x = i/j
	// Float division: float x = (float)i / j



	// When making a string, it's actually an array: 

	char yourName[] = "Freida Smith";

	// And we can print string lengths

	printf("%d\n", strlen(yourName));  // So the percentage is the placeholder and the other paramater you put in is what goes in the place holder.

	// We can compare strings also:

	char hisName[] = "John";

	if (strncmp(hisName, "John", 4) == 0) {  // Returns 0 if equal. Takes in the two strings to be compared, and their maximum comparison length.
		printf("Hello John!\n");
	}
	else {
		printf("You aren't John! Go away! \n");
	}

	// Lastly, we can concatenate strings

	char first[20] = "Hello "; // Ensure this string is big enough to add to the end
	char second[] = "World!";

	strncat(first, second, 6); // Using 6 since World! is 6 characters. Always make sure it's the right size

	printf("%s\n", first);



	// For loops

	int i;
	for (i = 0; i < 10; i++) { // Note: i++ increments i by 1 each time. Essentially i+=1
		printf("%d\n", i);
	}



	// While loops 

	int n = 0;
	while (n < 10) {
		printf("%d\n", n);
		n++;
	}



	// Infinite while loops.

	int p = 0;
	while (1) {
		p++;
		if (p == 10) {
			break; // The break command ends the loop
		}
	}


	// The continue command

	int m = 0;
	while (m < 10) {
		m++;

		// Check that m is odd 

		if (m % 2 == 1) {
			continue; // Goes back to the start of the while block
		}

		// You reach this if the number is even.
		printf("The number %d is even.\n", m);
	}


	// Calling my functions defined above main. 


	int theResult;
	int q = 5;
	theResult = square(q);
	printf("The square of %d is %d\n", q, theResult);



	// Calling my procedure defined above main.

	moo();



	/* Static and Dynamic Variables - Scope.

	* If I have a variable in a function then call that function from main, the value will stay the same and it will
	* change back to its normal value after the function has been called. We can prevent this by using the static keyword.
	* This means the variable will keep whatever value it has and won't reset back after the function is called.
	*/
	//-----------------------------------------------------------------------------------------------------------------------
	//int runner() {
		//int count = 0;  <--- This is a normal local variable 
		//count++;
		//return count;
	//}

	//printf("%d ", runner());
	//printf("%d ", runner());

	// ^^^ So if this code is called, it will output 11.

	//-----------------------------------------------------------------------------------------------------------------------

	// But with Static...

	//int runner() {
		//static int count = 0; <--- Static variable - duration changed
		//count++;
		//return count;
	//}

	//printf("%d ", runner());
	//printf("%d ", runner());

	// ^^^ So if this code is called, it will output 12.

	//-----------------------------------------------------------------------------------------------------------------------



	// We can also have static functions.


	/* By default, in C, functions are global meaning that they can be accessed in the file (source.c) and outside the file
	like if you had another source file i.e. source2.c */


	// We can make functions static so they can only be accessed inside the file that they are in. See below:

	//static void fun() { <--- Just chuck static infront!
		//printf("I am a static function.");
	//}



	// Very lastly, #DEFINE.

#define PI 3.14159

	// Now every time you write PI, the programme will sub 3.141592 in - saves mucking about!

	// To write to a file, see slide 12 of Lecture 1 - getting started!


	return 0; // This is saying that if 0 is returned, all ran well. If 1 was returned, it would be an error. 

}