C - Programming Language
This course covers the basics of programming in C. Work your way through the videos and we'll teach you everything you need to know to start your programming journey!

In One Video

Lesson 31
Author : Mike Dane
Last Updated : November, 2017


C Overview

C is a general purpose, staticly typed, imperative programming language that was founded in 1972 by Dennis Ritchie and Ken Thompson at Bell Labrotories.

C is a low level language meaning it provides constructs which map efficiently to typical machine instructions. Baiscally it’s a more user friendly way to write low level programs. Instead of pulling your hair out writing low level code in an assembly language, you can abstract a lot of the fuss and write equivalent programs in c

Because it’s so low level, many operating system kernals, and even other programming languages are implemented at least in part, using C. And many modern progrmaming languages today borrow syntax and best practices from C.

How C Runs

All c programs must utilize a compiler who’s job is to compile the c code down into machine code readable by the computer. So anytime you want to run a c program you have to compile it first.

C relies on the user to manage the program’s memory, and the syntax of C is largly influenced by the B programming language.

Choosing an IDE

Many developers choose to write C using a basic text editor, but there are also more specilized integrated development enviornments, some of the most popular include Code Blocks, Eclipse and Net Beans.

Code

Printing

Copyprintf("Hello\n");
printf("World");
printf("!\n");

Variables and Data Types

Copy/*
Names are case-sensitive and may begin with:
     letters, _
After, may include
     letters, numbers, _
Convention says
     Start with a lowercase word, then additional words are capitalized
     ex. myFirstVariable
*/
char testGrade = 'A';    // single 8-bit character.
char name[] = "Mike";    // array of characters (string)

// you can make them unsigned by adding "unsigned" prefix
short age0 = 10;         // atleast 16-bits signed integer
int age1 = 20;           // atleast 16-bits signed integer (not smaller than short)
long age2 = 30;          // atleast 32-bits signed integer
long long age3 = 40;     // atleast 64-bits signed integer

float gpa0 = 2.5;       // single percision floating point
double gpa1 = 3.5;       // double-precision floating point
long double gpa2 = 3.5;  // extended-precision floating point

int isTall;             // 0 if false, non-zero if true
isTall = 1;

testGrade = 'F';

printf("%s, your grade is %c \n", name, testGrade);
/*
%c	character
%d	integer number (base 10)
%e	exponential floating-point number
%f	floating-point number
%i	integer (base 10)
%o	octal number (base 8)
%s	a string of characters
%u	unsigned decimal (integer) number
%x	number in hexadecimal (base 16)
%%	print a percent sign
\%	print a percent sign
*/

Casting and Converting

Copyprintf("%d \n", (int)3.14);
printf("%f \n", (double)3 / 2);

Pointers

Copyint num = 10;
printf("%p \n", &num);

int *pNum = #
printf("%p \n", pNum);
printf("%d \n", *pNum);

Numbers

Copyprintf("%d \n", 2 * 3);       // Basic Arithmetic: +, -, /, *
printf("%d \n", 10 % 3);      // Modulus Op. : returns remainder of 10/3
printf("%d \n", 1 + 2 * 3);   // order of operations
printf("%f \n", 10 / 3.0);    // int's and doubles


int num = 10;
num += 100;                   // +=, -=, /=, *=
printf("%d \n",num);

num++;
printf("%d \n", num);

printf("%f \n", pow(2, 3));
printf("%f \n", sqrt(144));
printf("%f \n", round(2.7));

User Input

Copychar name[10];
printf("Enter your name: ");
fgets(name, 10, stdin);
printf("Hello %s! \n", name);

int age;
printf("Enter your age: ");
scanf("%d", &age);
printf("You are %d \n", age);

char grade;
printf("Enter your grade: ");
scanf("%c", &grade);
printf("You got an %c on the test \n", grade);

double gpa;
printf("Enter your gpa: ");
scanf("%lf", &gpa);
printf("Your gpa is %f \n", gpa);

Arrays

Copy// int luckyNumbers[6];
int luckyNumbers[] = {4, 8, 15, 16, 23, 42};
//        indexes:    0  1  2   3   4   5
luckyNumbers[0] = 90;
printf("%d \n", luckyNumbers[0]);
printf("%d \n", luckyNumbers[1]);

2 Dimensional Arrays

Copy// int  numberGrid[2][3];
int numberGrid[2][3] = { {1, 2, 3}, {4, 5, 6} };
numberGrid[0][1] = 99;

printf("%d \n", numberGrid[0][0]);
printf("%d \n", numberGrid[0][1]);

Functions

Copyint addNumbers(int num1, int num2);

int main(){
     int sum = addNumbers(4, 60);
     printf("%d \n", sum);

     return 0;
}

int addNumbers(int num1, int num2){
     return num1 + num2;
}

If Statements

Copyint isStudent = 0;
int isSmart = 0;

if(isStudent != 0 && isSmart != 0){
     printf("You are a student\n");
} else if(isStudent != 0 && isSmart == 0){
     printf("You are not a smart student\n");
} else {
     printf("You are not a student and not smart\n");
}

// >, <, >=, <=, !=, ==
if(1 > 3){
     printf("number omparison was true\n");
}

if('a' > 'b'){
     printf("character comparison was true\n");
}

Switch Statements

Copychar myGrade = 'A';
switch(myGrade){
     case 'A':
          printf("You Pass\n");
          break;
     case 'F':
          printf("You fail\n");
          break;
     default:
          printf("Invalid grade\n");
}

While Loops

Copyint index = 1;
while(index <= 5){
     printf("%d \n", index);
     index++;
}

index = 1;
do{
     printf("%d \n", index);
     index++;
}while(index <= 5);

For Loops

Copyfor(int i = 0; i < 5; i++){
     printf("%d \n", i);
}

Structs

Copystruct Book{
     char title[100];
     char author[100];
}

int main(){

      struct Book book1;
      book1.numPages = 600;
      strcpy( book1.title, "Harry Potter" );
      strcpy( book1.author, "JK Rowling");

      printf("%s \n", book1.title);

      return 0;
}