1、本節(jié)主題：數(shù)值型數(shù)據(jù)的存儲(chǔ)原理基本數(shù)據(jù)類型85類型關(guān)鍵字字節(jié)數(shù)位數(shù)取值整型signed int432-21474836482147483647signed short216-3276832767signed long432-21474836482147483647unsigned int4320 unsigned short216065535unsigned long4320 浮點(diǎn)型float432 (3.410-383.41038)double864 (1.710-3081.710308)long double1080 (1.210-49323.4104932)字符型char18對(duì) 2 要敏

2、感00641 = 21-1111283 = 22-12102567 = 23-131151215 = 24-14100102451012048127 = 27-161104096255 = 28-17111819232767 = 215-1810001638465535 = 216-1161000032768= 2153210000065536= 216整型數(shù)據(jù)的存儲(chǔ)方式為按二進(jìn)制數(shù)形式存儲(chǔ)（以2字節(jié)的short為例）signed short 型以補(bǔ)碼形式存放，最高位表示數(shù)值的符號(hào)（0為正，1為負(fù)）unsigned數(shù)值沒有符號(hào)，全部二進(jìn)制位表示數(shù)值本身。0111111111111111= 10

3、10111011110100符號(hào)位signed short中最大的正數(shù)某個(gè)signed short 型負(fù)數(shù)= -?1111111111111111unsigned short中最大的數(shù)=65535整型短整型(short) 整型(int) 長(zhǎng)整型(long)有符號(hào)(signed) 無符號(hào)(unsigned)實(shí)型：存儲(chǔ)大小決定取值范圍！存儲(chǔ)符號(hào)有符號(hào)(signed)【默認(rèn)】無符號(hào)(unsigned)短整型(short)2B2B整型(int)4B4B長(zhǎng)整型(long)4B4Bsignedshort-32768 32767unsigned short0 65535整型短整型(short) 整型(int

4、) 長(zhǎng)整型(long)有符號(hào)(signed) 無符號(hào)(unsigned)溢出初探#include int main()short a, b; a= 32760;printf(a=%dn,a); b = a + 10;printf(b=%dn,b); return 0;換了int，同類問題 仍然存在！浮點(diǎn)型: 存儲(chǔ)大小決定取值范圍和精度浮點(diǎn)型（實(shí)型）單精度型(float) 雙精度型(double) 長(zhǎng)雙精度型(long double) float f=1.987654321，f 變量真是1.987654321嗎？關(guān)鍵字字節(jié)數(shù)位數(shù)取值范圍有效數(shù)字float432 (3.410-383.41038)

5、約7位十進(jìn)制數(shù)double864 (1.710-3081.710308)約16位十進(jìn)制數(shù)long double1080 (1.210-49323.4104932)約19位十進(jìn)制數(shù)讓數(shù)學(xué)老師如何面對(duì)?#include int main()double a,b,c; a=1234567890.123456789; b=987654321.987654321;c=a+b;printf(%22.9lfn,a);printf(+ %22.9lfn,b);printf(-n);printf(= %22.9lfn,c); return 0;浮點(diǎn)數(shù)的存儲(chǔ)原理一個(gè)數(shù)X 的浮點(diǎn)形式（即科學(xué)計(jì)數(shù)法）表示為：XMrE

6、 M尾數(shù)，數(shù) X 的有效數(shù)字，其位數(shù)反映數(shù)據(jù)的精度 r基數(shù)，十進(jìn)制的基數(shù)為10，二進(jìn)制的基數(shù)為2 E階碼，確定了數(shù) X 的小數(shù)點(diǎn)的真實(shí)位置38.25 = 0.3825102(38.25)10=(100110.01)2=(.100110012110)2尾數(shù)M: .10011001階碼E: 110階碼E符號(hào)尾數(shù)M浮點(diǎn)？定點(diǎn)？浮點(diǎn)數(shù)：小數(shù)點(diǎn)位置浮動(dòng) 階碼：用定點(diǎn)整數(shù)表示浮點(diǎn)數(shù)中小數(shù)點(diǎn)的真實(shí)位置 尾數(shù)：用定點(diǎn)小數(shù)表示數(shù)據(jù)的有效位數(shù)(含符號(hào))定點(diǎn)數(shù)：固定小數(shù)點(diǎn)的純小數(shù)和純整數(shù) 符號(hào)數(shù)值符號(hào). 小數(shù)點(diǎn)位置數(shù)值. 小數(shù)點(diǎn)位置313029282726252423222120191817161514131211

7、109876543210階碼尾數(shù)IEEE754標(biāo)準(zhǔn)William Kahan類型存儲(chǔ)位數(shù)數(shù)符(s)階碼(E)尾數(shù)(M)總位數(shù)短實(shí)數(shù)(Single,Float)1位8位23位32位長(zhǎng)實(shí)數(shù)(Double)1位11 位52位64位延伸雙精度（不常用）1位15位64位80位關(guān)鍵字字節(jié)數(shù)位數(shù)取值范圍有效數(shù)字float432 (3.410-383.41038)約7位十進(jìn)制數(shù)double864 (1.710-3081.710308)約16位十進(jìn)制數(shù)long double1080 (1.210-49323.4104932)約19位十進(jìn)制數(shù)0.65-0.6的結(jié)果是等于0.05嗎？#include int main()doublea=0.65f;doubleb=0.6f;doublec=a - b;if