Character quantity includes character constant and character variable. A string constant is a sequence of characters enclosed in a pair of double quotes. The value of a character variable is a character constant, that is, a single character. The type specifier of a character variable is char. The format and writing rules of type description of character variables are the same as those of integer variables.
Floating-point type uses exponent to make the position of decimal point float up and down as needed, so it can flexibly represent a wider range of real numbers.
Double-precision floating-point type, which is similar to single-precision data type (float), but has higher precision than float, and the memory space occupied during compilation varies with different compilers. It is a double floating-point data type and a variable type representing real variables in C/C++.
Extended data
Double-precision floating-point type values can be converted to other types of integers or floating-point numbers, and vice versa. The last character of a double-precision floating-point constant can be added with "d" or "d". Its storage format is similar to floating point, the highest bit is sign bit, the second highest bit is exponent bit, and the last 52 bits are mantissa bit. ?
A double-precision type is a double-precision floating-point type. Compared with numerical model, it can provide higher numerical accuracy. It adopts floating-point type with fixed storage length, and each double-precision floating-point type data accounts for 8 bytes. Different from numerical data, its decimal point position is determined by the input data value and can only be used for fields in tables.
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