2-7 比较大小

#include <stdio.h>int main(void)
{int a, b, c, t;printf("请输入3个整数：");scanf("%d %d %d", &a, &b, &c);if (a > b){t = a;a = b;b = t;}if (a > c){t = a;a = c;c = t;}if (b > c){t = b;b = c;c = t;}printf("从小到大输出顺序为：%d ->%d ->%d\n", a, b, c);return 0;	
} 

2-8 高速公路超速处罚

#include <stdio.h>int main(void)
{double speed, basicSpeed, rate;printf("请输入车速值和车道限速值：");scanf("%lf %lf", &speed, &basicSpeed);rate = (speed - basicSpeed) / basicSpeed * 100;if (rate < 10){printf("正常车速");}else if (rate < 50){printf("罚款200元");}else{printf("吊销驾驶证");}return 0;	
} 

2-9 分段计算居民水费

#include <stdio.h>int main(void)
{double x, y;scanf("%lf", &x);if (x <= 0){y = 0;}else if (x <= 15){y = 4 * x / 3;}else{y = 2.5 * x - 17.5;}printf("y = %.2lf", y);return 0;	
} 

2-10 计算个人所得税

#include <stdio.h>int main(void)
{double tax, rate, salary;scanf("%lf", &salary);if (salary >= 0){if (salary <= 1600){rate = 0;}else if (salary <= 2500){rate = 0.05;}else if (salary <= 3500){rate = 0.1;}else if (salary <= 4500){rate = 0.15;}else{rate = 0.2;}tax = rate * (salary - 1600);		printf("tax = %.2lf", tax);}else{printf("salary can not below zero");}return 0;	
}