Editing Long double

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<code>long double</code> is a primitive floating-point data type in C (and subsequently C++) that is required by the standard to be at least as long as a <code>double</code>. That is, the values it can represent must be a superset of the values that a <code>double</code> can represent.

On many architectures, <code>long double</code> is identical to <code>double</code>, since <code>double</code> is usually a [[IEEE 754|binary64]] and many architectures do not support a longer floating-point data type. On Intel x86 machines, however, <code>long double</code> is often a 80-bit ''extended precision'' format that originated with the Intel 8087 numeric coprocessor. This format is almost exactly analogous to the [[IEEE 754]] formats, except that its significand does not carry an implicit leading 1. It consists of a sign bit, a 15-bit biased exponent field, and a 64-bit significand field. Because the x86 processors are little-endian, when this kind of number is stored in memory, the lowest-address 8 bytes are used for the significand, the next byte is used for the least significant 8 bits of the exponent, and the last byte contains the sign bit as the most significant bit, followed by the most significant 7 bits of the exponent.