Data Types in C
The first thing you need to know is that you can create variables to store values in. A variable is just a named area of storage that can hold a single value (numeric or character). C is very fussy about how you create variables and what you store in them. It demands that you declare the name of each variable that you are going to use and its type, or class, before you actually try to do anything with it.
In this section we are only going to be discussing local variables. These are variables that are used within the current program unit (or function) in a later section we will looking at global variables - variables that are available to all the program's functions.
There are four basic data types associated with variables:
int - integer: a whole number.
float - floating point value: ie a number with a fractional part.
double - a double-precision floating point value.
char - a single character.
The first thing you need to know is that you can create variables to store values in. A variable is just a named area of storage that can hold a single value (numeric or character). C is very fussy about how you create variables and what you store in them. It demands that you declare the name of each variable that you are going to use and its type, or class, before you actually try to do anything with it.
In this section we are only going to be discussing local variables. These are variables that are used within the current program unit (or function) in a later section we will looking at global variables - variables that are available to all the program's functions.
There are four basic data types associated with variables:
int - integer: a whole number.
float - floating point value: ie a number with a fractional part.
double - a double-precision floating point value.
char - a single character.
Vaious datatypes and their sizes
Data Type Memory (bytes) Range Format Specifier
short int 2 -32,768 to 32,767 %hd
unsigned short int 2 0 to 65,535 %hu
unsigned int 4 0 to 4,294,967,295 %u
int 4 -2,147,483,648 to 2,147,483,647 %d
long int 4 -2,147,483,648 to 2,147,483,647 %ld
unsigned long int 4 0 to 4,294,967,295 %lu
long long int 8 -(2^63) to (2^63)-1 %lld
unsigned long long int 8 0 to 18,446,744,073,709,551,615 %llu
signed char 1 -128 to 127 %c
unsigned char 1 0 to 255 %c
float 4 %f
double 8 %lf
long double 16 %Lf
Enumeration (or enum) in C
Enumeration (or enum) is a user defined data type in C. It is mainly used to assign names to integral constants, the names make a program easy to read and maintain.
enum State {Working = 1, Failed = 0};
// An example program to demonstrate working
// of enum in C
#include<stdio.h>
enum week{Mon, Tue, Wed, Thur, Fri, Sat, Sun};
int main()
{
enum week day;
day = Wed;
printf("%d",day);
return 0;
}
Output: 2
