How the floating-point type is stored in memory.

echo number_format(19.99 * 100, 20);    // output:1,998.99999999999977262632

Why is this so? How floating-point types are stored. My idea might be that floating-point types are inherently not exactly stored.
Solve this problem and know why intval the value is 1998 .

Reply content:

echo number_format(19.99 * 100, 20);    // output:1,998.99999999999977262632

Why is this so? How floating-point types are stored. My idea might be that floating-point types are inherently not exactly stored.
Solve this problem and know why intval the value is 1998 .

The storage accuracy of floating-point numbers is related to the system, and PHP typically uses the IEEE 754 double-precision format, which defaults to 20-bit effective precision. Floating point numbers

Floating Point Usage Guide

Floating-point type http://php.net/manual/zh/language.types.float.php with Chinese characters

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