What does 21f mean in C language?

"21f" in C language represents a single-precision floating point number with a value of 21.0, which represents a floating point number: Mantissa: 21 Base: 10 Exponent: 0 Binary representation: 0000000001111111100000000000000000000000000000000000000 Floating point value: 1.0 × 2 ^ 127 = 21.0

The meaning of 21f in C language

In C language, "21f" is a floating point constant, Represents a single-precision floating point number with value 21.0. It is expressed using scientific notation, where:

• "21" is the mantissa part of the floating point number, representing the value 21.
• "f" is the character after the mantissa, indicating that the constant is a single-precision floating point number.

In C language, single-precision floating-point numbers are stored in 32 bits and represent a range from -3.4e38 to 3.4e38. Therefore, "21f" represents a real number between -3.4e38 and 3.4e38.

Floating point number representation

Floating point numbers are represented using scientific notation, as follows:

<code>± 尾数 × 基数 ^ 指数</code>

Where:

• The mantissa is the decimal part of the floating point number.
• Base is usually 2 or 10.
• Exponent represents the scaling factor of the mantissa.

Format of single-precision floating-point numbers

Single-precision floating-point numbers in C language are stored in the following format:

<code>符号位 (1 位) | 指数位 (8 位) | 尾数位 (23 位)</code>

Where:

• The sign bit represents the sign of the floating point number (0 represents a positive number, 1 represents a negative number).
• The exponent bit stores the exponent (using frameshift representation).
• Mantissa bit stores the mantissa.

The binary representation of "21f" is:

<code>00000000 | 01111111 | 10000000000000000000000</code>

Among them:

• The sign bit is 0, indicating a positive number.
• The exponent bit is 01111111, which means the exponent is 127 (offset exponent).
• The mantissa digit is 10000000000000000000000, which means the mantissa is 1.0.

Therefore, the floating point value of "21f" is:

<code>1.0 × 2 ^ 127 = 21.0</code>

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