c++ double code example

Example 1: float in c++

float contains less storage than a double. 
float p = 25.0;
double p = 25.0;

Example 2: casting to a double in c++

double x;
x = (double) 25;

Example 3: double to float c++

double v1 = 20120313.0;
    float v2 = (float) v1;