The following table lists the valid typespecifiers:
void

an empty or NULL value.

char, signed char

a variable to store a basic character in the character set. The value is either signed or nonnegative.

unsigned char

Same as char, but unsigned values only.

short, signed short, short int, signed short int

a 16bit short signed integer.

unsigned short, unsigned short int

an unsigned short integer.

int, signed, signed int, long, signed long, long int, signed long int, or no type specifier

a 32 bit signed integer. If no type specifier is given, then this is the default.

unsigned long, unsigned long int, unsigned int, unsigned

same as int, but unsigned values only.

long long, signed long long

a 64 bit signed integer.

unsigned long long

same as long long, but unsigned values only.

float

a floatingpoint number. Consists of a sign, a mantissa (number greater than or equal to 1), and an exponent. The mantissa is taken to the power of the exponent and then given the sign. The exponent is also signed allowing extremely small fractions. The mantissa gives it a finite precision.

double

a more accurate floatingpoint number than float. Normally twice as many bits in size as float. Size depends on platform and application.

long double

increases the size of double.

The following table shows the minimum and maximum ranges of the various data types with their typespecifiers for most platforms.
Type

Size

Range

unsigned char

8 bits

0 to 255

char

8 bits

128 to 127

unsigned short

16 bits

0 to 65,535

short int

16 bits

32,768 to 32,767

int

32 bits

2,147,483,648 to 2,147,483,647

unsigned long

32 bits

0 to 4,294,967,295

long

32 bits

2,147,483,648 to 2,147,483,647

long long  64 bits  –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 
unsigned long long  64 bits  0 to 18,446,744,073,709,551,615 
float

32 bits

1.17549435 * (10^38) to
3.40282347 * (10^+38) 
double

64 bits

2.2250738585072014 * (10^308) to 1.7976931348623157 * (10^+308)

long double

80 bits

3.4 * (10^4932) to 1.1 * (10^4932)
