第3章運(yùn)算符與表達(dá)式

1、哈爾濱工業(yè)大學(xué)哈爾濱工業(yè)大學(xué)計(jì)算機(jī)科學(xué)與技術(shù)學(xué)院計(jì)算機(jī)科學(xué)與技術(shù)學(xué)院蘇小紅蘇小紅2021-11-122/512021-11-123/512021-11-124/51Example:2021-11-125/512021-11-126/51Example:浮點(diǎn)數(shù)除法浮點(diǎn)數(shù)除法(Floating Division) or or both are floats整數(shù)除法整數(shù)除法(Integer Division) and are integers2021-11-127/51Example:2021-11-128/51Example:2021-11-129/512021-11-1210/51Example

2、:1152101remainderresult2021-11-1211/51Example:-115-2-10-1remainderresult2021-11-1212/51Example:11-5-210 1remainderresult2021-11-1213/51Example:2021-11-1214/512021-11-1215/512021-11-1216/51Example: 2021-11-1217/51Example:2021-11-1218/51Example:2021-11-1219/512021-11-1220/512021-11-1221/51關(guān)鍵是如何分離個(gè)位、關(guān)鍵

3、是如何分離個(gè)位、十位和百十位和百位數(shù)字？位數(shù)字？2021-11-1222/51#include main() int x = 153, b0, b1, b2, sum; b2 = x / 100; b1 = (x - b2 * 100) / 10; b0 = x % 10; sum = b2 + b1 + b0; printf(b2=%d, b1=%d, b0=%d, sum=%dn, b2, b1, b0, sum);2021-11-1223/512021-11-1224/512021-11-1225/51Example:num = num + 5;num1520Example:num +=

4、 5;2021-11-1226/51已知已知 int a = 3;執(zhí)行執(zhí)行 a += a -= a * a 后，變量后，變量a的值？的值？ a += a -= a * a a += a -= 9 a += -6 a = -12執(zhí)行執(zhí)行 a += a -= a *= a 后，變量后，變量a的值？的值？ a += a -= a *= a a += a -= 9 a += 0 a = 02021-11-1227/51OperationExamples of expressionDescription+=num += 5;num = num + 5;-=num -= 5;num = num 5;*=n

5、um *= 5;num = num * 5;/=num /= 5;num = num / 5;%=num %= 5;num = num % 5;2021-11-1228/512021-11-1229/512021-11-1230/51Example:j = +i - 2i5similar to j? 462021-11-1231/51Example:j = i+ - 2i5similar to j? 362021-11-1232/51int a=3;printf(%d, -a+);a3similar to 42021-11-1233/512021-11-1234/51circumference

6、 = 33.300854area = 88.247263#include main() double r = 5.3; printf(circumference = %fn, 2*3.14159*r); printf(area = %fn, 3.14159*r*r);2021-11-1235/51#include main() double r; printf(Input r:); scanf(%lf, &r); printf(circumference = %fn, 2*3.14159*r); printf(area = %fn, 3.14159*r*r); Input r: 5.3

7、 circumference = 33.300854 area = 88.247263在程序中直接使用的常數(shù)稱在程序中直接使用的常數(shù)稱為幻數(shù)為幻數(shù)(Magic Number) 2021-11-1236/512021-11-1237/512021-11-1238/51#include main() double r; printf(Input r:); scanf(%lf, &r); printf(circumference = %fn, 2*PI*r); printf(area = %fn, PI*r*r);2021-11-1239/51#include #define PI 3.14

8、159;#define R 5.3;main()printf(area = %fn, PI * R * R);printf(circumference = %fn, 2 * PI * R);相當(dāng)于執(zhí)行相當(dāng)于執(zhí)行#include main()printf(area = %fn, 3.14159;*5.3;*5.3;);printf(circumference = %fn, 2*3.14159;*5.3;);2021-11-1240/51#include main() const double PI = 3.14159; double r; printf(Input r:); scanf(%lf,

9、 &r); printf(circumference = %fn, 2*PI*r); printf(area = %fn, PI*r*r);2021-11-1241/51doublefloatlongunsignedintchar，short低高2021-11-1242/512021-11-1243/512021-11-1244/51Example: int x = 10;float y;y = (float)x;x10y?10.0000002021-11-1245/51Example: int total, number;float average;average = total / number;total15number2average?7.000000兩個(gè)整數(shù)運(yùn)算的結(jié)果兩個(gè)整數(shù)運(yùn)算的結(jié)果還是整數(shù)，不是浮點(diǎn)數(shù)還是整數(shù)，不是浮點(diǎn)數(shù)2021-11-1246/51Example: int total, number;float average;average = (float)total / number;total15number2average?7.5000002021-11-1247