C语言程序设计PPT电子课件教案-04_循环语句嵌套及应用.ppt

lesson 4 循环语句嵌套及应用,4,本课内容,四舍五入,循环嵌套与 break 语句,九九表、完数,实型：float、double,强制类型转换,for语句的一般格式,for (表达式1; 表达式2; 表达式3) 语句 ,例如，下面的程序计算1至100的和： for (s = 0, i = 1; i = 100; i+) s += i;,for语句嵌套,for (表达式1; 表达式2; 表达式3) 语句1 for (表达式1; 表达式2; 表达式3) 语句2 语句3 ,for语句嵌套,for (a = 1; a = 9; a+) printf(“%d: “, a); for (b = 1; b = 9; b+) printf(“%d,“, b); printf(“n“); ,a,1:,1,2,3,4,5,6,7,8,9,2:,1,b,1,2,3,4,5,6,7,8,9,10,2,1,2,3,4,5,6,7,8,9,3,9:,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,乘法九九表,for (a = 1; a = 9; a+) for (b = 1; b = 9; b+) printf(“%d*%d=%d “, b, a, a*b); printf(“n“); ,a = 1,b = 1, 2, 3, ., 9, 2, 3, ., 9,1*1=1,2*1=2,3*1=3,9*1=9,1*2=2,2*2=4,3*2=6,9*2=18,1*9=1,2*9=18,3*9=27,9*9=81,数字方阵,1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5,#define n 5 for (a = 1; a = n; a+) for (b = 1; b = n; b+) printf(“%d“, a); printf(“n“); ,循环嵌套8-1,2008.9.27以下程序的运行结果是 int i, j; for (i = 3; i = 1; i-) for (j = 1; j = 2; j+) printf(“%d“, i + j); printf(“n“); a)234 b)432 c)23 d)45 345 543 34 34 45 23,循环嵌套8-2,2007.4.24以下程序的运行结果是 for (i = 1; i 3; i+) for (j = i; j 3; j+) printf(“%d*%d=%d “, i, j, i*j); printf(“n“); a)1*1=1 1*2=2 b)1*1=1 1*2=2 2*1=2 2*2=4 c)1*1=1 d)1*1=1 1*2=2 2*2=4 2*1=2 2*2=4,循环嵌套8-3,2006.4.15以下程序的运行结果是 int i, j, n = 4, t = 1; for (i = 1; i = n; i+) for (j = 1; j = n-i+1; j+) printf(“%2d“, t); t+; printf(“n“); ,1 2 3 4 5 6 7 8 9 10,循环嵌套8-4,2007.9.24以下程序运行后，m的值是 int i, j, m = 55; for (i = 1; i = 3; i+) for (j = 3; j = i; j+) m = m % j;,1,2009.3.20以下程序的运行结果是 for (i = 0; i 4; i+, i+) for (k = 1; k 3; k+); printf(“*“);,*,循环嵌套8-5,2010.3.20以下程序的运行结果是 int i, j, m = 1; for (i = 1; i 0; j-) if (i*j 3) break; m *= i*j; printf(“m = %dn“, m);,m = 6,循环嵌套8-6,例以下程序运行后，s的值是 int i, j, s; for (i = 3; i = 1; i-) s = 0; for (j = 1; j = i; j+) s += i * j; ,1,循环嵌套8-7,2004.4.25以下程序运行后，n的值是 int i, n = 0; for (i = 2; i 5; i+) do if (i % 3) continue; n+; while (!i); n+; ,4,循环嵌套8-8,2006.4.32以下程序运行后，x的值是 int i, j, x = 0; for (i = 0; i 2; i+) x+; for (j = 0; j = 3; j+) if (j % 2) continue; x+; x+; ,8,完数,完数 = 因子之和 例：6 = 1 + 2 + 3,素数,素数,输出菱形,* * * *,* * * *,行号 空格 星号 1 3 1 2 2 3 3 1 5 4 0 7,行号 空格 星号 1 0 7 2 1 5 3 2 3 4 3 1,空 = 4 - 行,空 = 行 - 1,星 = 2*行 - 1,星 = 9 - 2*行,圆周率,while (v 0.000001) s += t*v; m += 2; v = 1/m; t = -t; ,printf(“pai = %.10f“, 4 * s);,s = 1/1,double s = 0, m = 1, v = 1/m, t = 1;,m = 3,v = 1/3,t = -1,-1/3, 5, 7,1/5,1/7, +1, -1,+1/5,-1/7,2009.3.6以下表达式的值是： (int)(double)(5/2) + 2.5),强制类型转换,格式：(数据类型说明符)(表达式) (int)(x + y) / 把x + y的结果转换为int (int)x + y / 把x的值转换为int，再加y int(x + y) / 错误,4,2009.9.14以下表达式的值是： (double)9/2 + 0.7) - 9%2,4.2,2011.3.6以下表达式的值是： (int)(double)(3/2) + 0.5 + (int)1.99 * 2),3,四舍五入3-1,2345.67,double x = 23.4567; x = (int)(x * 100 + 0.5) / 100.0;,printf(“x = %f“, x);,= 23.46,2346.17,2346,23.46,x = 23.460000,四舍五入3-2,2345.22,double x = 23.4522; x = (int)(x * 100 + 0.5) / 100.0;,printf(“x = %f“, x);,= 23.45,2345.72,2345,23.45,x = 23.450000,四舍五入3-3,45.678,int a = 45678; a = (int)(a / 1000.0 + 0.5) * 1000;,printf(“a = %d“, a);,= 46000,46.178,46,46000,a = 46000,实型常量,1.小数形式。如: 0.12, .12, 12., 12.0 2.指数形式。如: 12e3和12e3 都代表 12103 注意：字母e之前必须有数字，且e后面的指数必须为整数。,2005.4.15以下不合法的数值常量是 a)1.234e04 b)1.234e0.4