C Language. W3Schools in English. Lessons for beginners

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C Syntax


You have already seen the following code a couple of times in the first chapters. Let's break it down to understand it better:


#include <stdio.h>

int main() {
  printf("Hello World!");
  return 0;
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Example explained

Line 1: #include <stdio.h> is a header file library that lets us work with input and output functions, such as printf() (used in line 4). Header files add functionality to C programs.

Don't worry if you don't understand how #include <stdio.h> works. Just think of it as something that (almost) always appears in your program.

Line 2: A blank line. C ignores whitespace. But we use it to make the code more readable.

Line 3: Another thing that always appear in a C program, is main(). This is called a function. Any code inside its curly brackets {} will be executed.

Line 4: printf() is a function used to output/print text to the screen. In our example it will output "Hello World".

Note that: Every C statement ends with a semicolon ;

Note: The body of int main() could also been written as:
int main(){printf("Hello World!");return 0;}

Remember: The compiler ignores whitespaces. However, multiple lines make the code more readable.

Line 5: return 0 ends the main() function.

Line 6: Remember to add the closing curly bracket } to actually end the main function.