Floating-point variables are declared using the 'float' type specifier, and floating point constants are indicated by a decimal point:
float standard_deviation;
standard_deviation = 0.;
Double-precision floating-point variables use the 'double' specifier, usually occuping 64 bits instead of a float's 32 bits. Floating-point constants are double by default. In Think C, arithmetic using doubles is faster that that using float variables.
An alternate representation of floating-point constants uses "e" notation to indicate the number is to be multiplied by 10 raised to the indicated exponent: