关于c语言大一新生基础知识解答

Question

Answer 1

这么算你看看是你想要的不？
-45.85
单精度组成：1bit符号位+8bit指数部分+23bit小数部分

负值 符号位 1

整数45的二进制：101101

小数
0.85 x2 = 1.7 1
0.7 x2 = 1.4 1
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
…

可写成 45.85 = 101101.11011001100110011001100110

变科学计数法
101101.11011001100110011001100110 = 1.0110111011001100110011001100110 x 2^5

根据IEEE规范 指数由8bit表示，值127为0，值128为1，
5次方是 127+5 = 132
132的二进制10000100
指数部分10000100

尾部 1. 0110111011001100110011001100110去掉1
0110111011001100110011001100110
拼一起 单精度组成：1bit符号位+8bit指数部分+23bit小数部分
1 10000100 01101110110011001100110
-45.85 单精度二进制表示为
1 10000100 01101110110011001100110

双精度组成：1bit符号位+11bit指数部分+52bit小数部分

负值 符号位 1

整数45的二进制：101101

小数
0.85 x2 = 1.7 1
0.7 x2 = 1.4 1
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
0.4x2 = 0.8 0
0.8x2 = 1.6 1
0.6x2 = 1.2 1
0.2x2 = 0.4 0
…

45.85 = 101101.1101100110011001100110011001100110011001100110011001100110

根据IEEE规范 指数由11bit表示，值1023为0，值1024为1，

5次方是 1023+5 = 1028
1028的二进制100 0000 0100
指数部分100 0000 0100
尾部 1.011011101100110011001100110011001100110011001100110011001100110
去掉1
011011101100110011001100110011001100110011001100110011001100110
拼一起 双精度组成：1bit符号位+11bit指数部分+52bit小数部分
1 10000100 0110111011001100110011001100110011001100110011001100
-45.85 双精度二进制表示为
1 10000100 0110111011001100110011001100110011001100110011001100