C语言程序设计课件3

1、中国石油大学中国石油大学计算机与通信工程学院计算机与通信工程学院于广斌于广斌2022-2-52/512022-2-53/512022-2-54/51Example:2022-2-55/512022-2-56/51Example:浮点数除法浮点数除法(Floating Division) or or both are floats整数除法整数除法(Integer Division) and are integers2022-2-57/51Example:2022-2-58/51Example:2022-2-59/512022-2-510/51Example:1152101remainderres

2、ultInteger Division2022-2-511/51Example:-115-2-10-1remainderresultInteger Division2022-2-512/51Example:11-5-210 1remainderresultInteger Division2022-2-513/51Example:2022-2-514/512022-2-515/512022-2-516/51Example: 2022-2-517/51Example:2022-2-518/51Example:2022-2-519/512022-2-520/512022-2-521/512022-2

3、-522/51关键是如何分离个位、十位和百位数字？关键是如何分离个位、十位和百位数字？2022-2-523/51#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);2022-2-524/512022-2-525/51Example:num = num + 5;num1520Example:num += 5

4、;2022-2-526/51已知已知 int a = 3;执行执行 a += a -= a * a 后，变量后，变量a的值？的值？ a += a -= a * a a += a -= 9 a += -6 a = -12执行执行 a += a -= a *= a 后，变量后，变量a的值？的值？ a += a -= a *= a a += a -= 9 a += 0 a = 02022-2-527/51OperationExamples of expressionDescription+=num += 5;num = num + 5;-=num -= 5;num = num 5;*=num *=

5、5;num = num * 5;/=num /= 5;num = num / 5;%=num %= 5;num = num % 5;2022-2-528/512022-2-529/512022-2-530/51Example:j = +i - 2i5similar to j? 462022-2-531/51Example:j = i+ - 2i5similar to j? 362022-2-532/51int a=3;printf(%d, -a+);a3similar to 42022-2-533/512022-2-534/51circumference = 33.300854area = 8

6、8.247263#include main() double r = 5.3; printf(circumference = %fn, 2*3.14159*r); printf(area = %fn, 3.14159*r*r);2022-2-535/51#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 circumference = 33.30

7、0854 area = 88.247263在程序中直接使用的常数称在程序中直接使用的常数称为幻数为幻数(Magic Number) 2022-2-536/512022-2-537/512022-2-538/51#include #define PI 3.14159main() double r; printf(Input r:); scanf(%lf, &r); printf(circumference = %fn, 2*PI*r); printf(area = %fn, PI*r*r);2022-2-539/51#include #define PI 3.14159;#define

8、R 5.3;main()printf(area = %fn, PI * R * R);printf(circumference = %fn, 2 * PI * R);相当于执行相当于执行#include main()printf(area = %fn, 3.14159;*5.3;*5.3;);printf(circumference = %fn, 2*3.14159;*5.3;);2022-2-540/51#include main() const double PI = 3.14159; double r; printf(Input r:); scanf(%lf, &r); prin

9、tf(circumference = %fn, 2*PI*r); printf(area = %fn, PI*r*r);2022-2-541/51u 强制类型转换运算符强制类型转换运算符u 表达式与赋值中的自动类型转换表达式与赋值中的自动类型转换2022-2-542/51doublefloatlongunsignedintchar，short低高2022-2-543/512022-2-544/512022-2-545/51Example: int x = 10;float y;y = (float)x;x10y?10.0000002022-2-546/51Example: int total, number;float average;average = total / number;total15number2average?7.000000两个整数运算的结果两个整数运算的结果还是整数，不是浮点数还是整数，不是浮点数2022-2-547/51Example: int total, number;float average;average = (float)total / number;total15number2aver