Table of Contents:
Recap
In the last blog, we configured our environment to use the C language. We had to use a simple code example in order to run a program:
#include <stdio.h>
int main()
{
printf("Hello World!");
return 0;
}
Now we'll learn a bit about the basic program structure in C.
Program Structure
Case Sensitivity
Everything in C is case sensitive. Lowercase and uppercase code matters here. If something is out of place, there will be compilation errors.
Semicolons
Every statement in C ends with a semicolon. Statements are lines of code within the code block. The code block is set by curly braces {}
. The statements are within the code block above:
printf("Hello World!");
return 0;
Those are required to end with a semicolon, otherwise, there will be compilation errors.
Indentation
Although the code above doesn't need to be indented in any way, it is written to be readable. Readable code is easy to understand. When you don't write readable code, it will be difficult to follow later on.
Comments
Comments will be ignored by the compiler. They won't produce errors. There are two ways to write comments, multi-line and single-line.
/* Multi-line */
// Single-line
The main
Function
In the example above, main
is a function. The parenthesis after the name main()
denotes that it is a function. The main
function is special, as it is the first function that runs upon program execution. You are only allowed to write one main
function.
int
If you're wondering what the int
is before the main()
function, that is used to define what the function will return. It is a return type. There are other ones besides int
, but int
defines main()
as a function that will return an integer.
The function above returned zero. That is an exit code. Zero is the exit code for EXIT_SUCCESS
.
Preprocessor
The C Preprocessor is an instruction sent to the compiler before the actual compilation takes place. It will analyze special statements in your code before the program runs.
They are usually defined at the top of a code file but can actually be placed anywhere in the code. Preprocessor statements begin with a pound sign #
and follow with a directive. There are many different directives.
The #include
directive was used above in the code example:
#include <stdio.h>
The #include
statement is a preprocessor directive that allows you to include code from other locations. It means that the code you're writing is dependent on code from another file.
stdio.h
is a file name. This is a header file. The #include
directive is going to include filenames ending with a .h
extension. The <stdio.h>
header file is a part of the C Standard Library. It stands for standard input-output. It provides functionality for displaying input and output.
<stdio.h>
allows us to use the printf
function. Without <stdio.h>
, the program wouldn't compile.
You can also write the name of the file in two ways:
// 1.) #include <stdio.h>
// 2.) #include "stdio.h"
Thank you for reading!
Top comments (0)