C provides float, double, and long double for representing floating-point values. These types differ primarily in their precision and range, with the exact representation and limits depending on the implementation.

#include <stdio.h>

int main()
{
    float a = 3.14f;
    double b = 3.1415926535;
    long double c = 3.141592653589793L;

    printf("float       = %.9f\n", a);
    printf("double      = %.10f\n", b);
    printf("long double = %.15Lf\n", c);

    return 0;
}

Example Output #

The exact precision and output can vary by implementation:

float       = 3.140000105
double      = 3.1415926535
long double = 3.141592653589793

Explanation #

float is generally used when lower storage requirements are more important than precision:

float a = 3.14f;

The f suffix makes 3.14f a float constant.

double provides at least as much precision and range as float:

double b = 3.1415926535;

A floating-point constant without a suffix has type double.

long double provides at least as much precision and range as double:

long double c = 3.141592653589793L;

The L suffix specifies a long double constant.

Floating-Point Type Reference #

The C standard specifies minimum characteristics rather than requiring these common sizes.

Floating-Point Literal Suffixes #

Floating-point values are not generally exact representations of decimal fractions. For example, a value such as 0.1 may require rounding when represented in a binary floating-point format.