C as a second language.

I have been writing code in some form for 11 years. Something that I do often is pick up another programming language in an attempt to learn new things and understand programming at a deeper level. When learning a new programming language there is always this period at the start where I want a quick start guide that will quickly go over the basic concepts of a language so I can start writing code straight away.

This post will serve as that guide.

Note: I am not an expert at C, I am learning along with you. I simply am curating the things that I have learned so that those the come after me can jump in a bit faster.

Why should you learn C?

• As of 5/12/25 C ranks as 3rd in the TIOBE index for the most popular language today
• C excels at giving the programmer full control of the operating system and its memory
• C is considered the lingua franca of the programming world, learning C can help you understand programming at a deeper level
• Correctly written C is very fast and serves as a fundamental skill in systems and other low level programming.

History of and Facts about C

• C was created in 1972 by Dennis Ritchie as a successor to the language B
• By the 1980s C gained massive traction and popularity
• C was standardized in 1989 by the American National Standards Institute (ANSI)

C Hello World Example

Including this in a quickstart guide only as a way to give you a functioning program straight away and to see how some C code looks in action.

#include <stdio.h>
int main() {
    printf("Hello World");
    return 0;
}
Code language: C++ (cpp)

• #include <stdio.h> – This line includes the header file for the standard I/O library. This includes the definition for printf.
• int main() – The main function which serves as the entry point to the program.
• printf(“Hello World”) – Prints out the text and adds a newline character at the end.
• return 0 – Exit the program and return no errors.

Data Types

Data types in C

• int
  • Range: -2,147,483,648 to 2,147,483,647
  • Size: 4 Bytes
• char
  • Range: -127 to 127 or 0 to 255
  • Size: 1 Byte
• float
  • Range: 1.2E-38 to 3.4E+38
  • Size: 4 Bytes
• double
  • Range: 1.7E-308 to 1.7E+308
  • Size: 8 Bytes
• void
  • Used to indicate the absence of a value
  • Can only be used for pointers and function return types

Variable Declaration

How to declare a variable in C

TYPE IDENTIFIER = VALUE;

int main() {
    int age = 42;
    float cash = 5322.47;
    double pi = 3.14;
    
    return 0;
}Code language: C++ (cpp)

Arrays

How to create and use an array in C

Array Declaration in C

TYPE IDENTIFIER[NUMBER_OF_ELEMENTS];

int main() {
    //Creates an array of type int
    //Contains 4 elements
    int ages[4];
    
    return 0;
}Code language: C++ (cpp)

Array Initialization in C

Initializing an array in C is very simple and similar to declaration.

int main() {
    int ages[4] = {29,38,42,19};
    //You can omit the size when 
    //initializing on the same line
    int ages[] = {29,38,42,19};
    //Init all values to 0 (Or something else)
    int ages[4] = {0};
    
    return 0;
}Code language: C++ (cpp)

Functions

How to create and use a function in C

Function Declaration in C

[KEYWORDS][RETURN TYPE][IDENTIFIER](PARAMETERS)

int sum(int num1, int num2){
    return num1 + num2;
}Code language: JavaScript (javascript)