C Basics

programming C MOC

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Commands in C end with a ;.

Functions use a code block enclosed by {}, so indentation and new lines do not matter.

Main Function

C’s main entry point for a program is the main function. Returning a 0 means the function finished successfully, but a higher number refers to a specific error.

int main() {
	return(0);
}

Importing Libraries

Libraries are imported with #include:

#include <stdio.h>
 
int main() {
	puts("Hello, World!");
	return(0);
}

Printing

Using puts()

The standard input output library stdio.h is very common.

#include <stdio.h>
 
int main() {
	puts("Hello, World!");
	return(0);
}

Using printf()

printf() is another method in stdio.h for formatting. Unlike puts(), it does not output with a \n new line character.

• %s: String
• %c: Character
• %d: Integer
• %f: Float
  • %.2f: Two decimal precision
• %u: Unsigned
• %lf: Double
• %o: Octal
• %x: Hexadecimal
• %p: Pointer

#include <stdio.h>
 
int main() {
    puts("One.");
    puts("Two.");
    printf("%s", "Three.");
    printf("%s", "Four.");
    return(0);
}
/* Output:
One.
Two.
Three.Four.

Comments

/*
This is a simple C program that uses stdio.h to output some text.
*/
#include <stdio.h
 
// Entrypoint, strictly typed
int main() {
	puts("Hello World") // One way to output content
	return(0); // return 0 to indicate success
}

Single Line Comments

C uses // for comments, which are ignored when compiling.

Multi-line Comments

Multi-line Comments use /* and */ delimiters