Keywords and Identifiers

Keywords in C are reserved words that have special meanings. They cannot be used as identifiers. Some examples of keywords include:

Category	Keywords
Data Types	int, float, char, double, void
Control Flow	if, else, switch, case, for, while, do
Storage Classes	auto, extern, static, register
Modifiers	short, long, signed, unsigned
Others	return, break, continue, sizeof, typedef, struct, enum, union, const, volatile, default, goto

Identifiers are the building blocks of a program. Identifiers are unique names that are assigned to variables, structs, functions, and other entities. They are used to uniquely identify the entity within the program.

Rules for Defining Identifiers:

They must begin with a letter or underscore, followed by letters, digits, or underscores.
It should not be a keyword.
It must not contain white space.
They must begin with a letter or underscore, followed by letters, digits, or underscores.

Code Example: Using Keywords and Identifiers


#include <stdio.h>
int main() {
    int myNumber = 10;            // myNumber as an Identifier
    if (myNumber > 0) {          // if as Keyword
        printf("Positive Number");
    }
    return 0;
}

Output

Positive Number