算数运算符
#include
using namespace std;
/*
算术运算符: + - * / % ++ --
赋值运算符: = += -= *= /= %=
比较运算符: == != < > <= >=
逻辑运算符: ! && ||
*/
int main16() {
//加减乘除
int a1 = 10;
int b1 = 4;
cout << a1 + b1 << endl;
cout << a1 - b1 << endl;
cout << b1 - a1 << endl;
cout << a1 / b1 << endl;//两个整型相除(除数不能是0),结果依然是整型(直接舍去小数点后面的数字)
cout << a1 % b1 << endl;//浮点型不能做取余
double d1 = 0.5;
double d2 = 0.22;
cout << d1 / d2 << endl;
//前置递增(先让变量加一,再进行表达式的运算),后置递增(先进行表达式的运算,后让变量加一)
int a2 ;
int a3 = a2 = 10;
int b2 = ++a2 * 10;
int b3 = a3++ * 10;
cout << "b2=" << b2 << endl;
cout << "a2=" << a2 << endl;
cout << "b3=" << b3 << endl;
cout << "a3=" << a3 << endl;
//赋值运算
int c, c1, c2,c3;
c = c1 = c2 = c3 = 100;
c += 10;//c=c+10;
c1 -= 10;//c=c-10;
c2 /= 10;//c=c/10;
c3 %= 10;//c=c%10;
cout << "c=" << c << endl;
cout << "c1=" << c1 << endl;
cout << "c2=" << c2 << endl;
cout << "c3=" << c3 << endl;
//比较运算符 == != < > <= >=
int A1 = 10;
int B1 = 20;
cout << (A1 == B1) << endl;
cout << (A1 != B1) << endl;
cout << (A1 <= B1) << endl;
cout << (A1 >= B1) << endl;
//逻辑运算符 ! && ||
cout << !A1 << endl;//只要不是0,其余数都为真;
cout << !!A1 << endl;
cout << A1 << endl;
cout << (A1 && B1) << endl;
cout << ((A1 > 2) && (B1 > 30)) << endl;
cout << ((A1 > 2) || (B1 > 30)) << endl;
system("pause");
return 0;
}
对程序流程结构的理解
#include
using namespace std;
/*
顺序结构:按循序执行 不发生转跳
选择结构:依据条件选择执行
循环结构:依据条件循环多次执行
*/
int main24() {
int a ;
cout << "请输入一个分数" << endl;
cin >> a ;
cout << "你的分数为:" << a << endl;
if (a > 600)//if条件语句后面不能加分号(;)
{
cout << "恭喜你考上一本大学" << endl;
if (a >= 700)
{
cout << "你能考入清华大学" << endl;
}
else if (a >= 680)
{
cout << "你能考入北京大学" << endl;
}
else if (a >= 650)
{
cout << "你能考入人民大学" << endl;
}
}
else if (a >= 500)
{
cout << "恭喜你考上了二本大学" << endl;
}
else if (a >= 400)
{
cout << "你考上了三本大学" << endl;
}
else
{
cout << "遗憾,你没考上本科" << endl;
}
system("pause");
return 0;
}
例子:三只小猪称体重
#include
using namespace std;
int maintest1() {
int a, b, c;
cout << "请依次输入三只小猪的体重" << endl;
cin >> a;
cin >> b;
cin >> c;
if (a > b)
{
if (a > c)
{
cout << "第一只小猪最重,重达" << a << "kg" << endl;
if (b > c)
{
cout << "第二只小猪次之,重达" << b << "kg" << endl;
cout << "第三只小猪最轻,重达" << c << "kg" << endl;
}
else
{
cout << "第三只小猪次之,重达" << c << "kg" << endl;
cout << "第二只小猪最轻,重达" << b << "kg" << endl;
}
}
}
else if (b > c)
{
cout << "第二只小猪最重,重达" << b << "kg" << endl;
if (a > c)
{
cout << "第一只小猪次之,重达" << a << "kg" << endl;
cout << "第三只小猪最轻,重达" << c << "kg" << endl;
}
else
{
cout << "第三只小猪次之,重达" << c << "kg" << endl;
cout << "第一只小猪最轻,重达" << a << "kg" << endl;
}
}
else
{
cout << "第三只小猪最重,重达" << c << "kg" << endl;
cout << "第二只小猪次之,重达" << b << "kg" << endl;
cout << "第一只小猪次之,重达" << a << "kg" << endl;
}
system("pause");
return 0;
}
三目运算符和switch语句
#include
using namespace std;
int main29()
{
//三目运算符
int a = 10;
int b = 20;
int c;
c = (a > b ? a : b);//如果a>b,返回a给c,否则返回b给c。
(a > b ? a : b) = 100;//三目运算符可以继续赋值
cout << "c=" << c << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
//switch语句
//switch缺点,只能判断整型和字符型,不可以是一个区间。
//优点,结构清晰,执行效率高。
cout << "请给这个个电影打分" << endl;
int score;
cin >> score;
switch (score)
{
case 10:
cout << "你认为这个电影是经典电影" << endl;
break;//退出当前分支
case 9:
cout << "你认为这个电影很好看" << endl;
break;//退出当前分支
case 8:
cout << "你认为这个电影很好看" << endl;
break;//退出当前分支
default:
cout << "垃圾电影" << endl;
}
system("pause");
return 0;
}
while循环语句
#include
using namespace std;
//time时间随机数种子需要头文件#include
int main31()
{
//while循环结构
int a = 0;
while (a < 10)
{
cout << a << endl;
a++;
}
//猜数字游戏
int b=rand() % 100 + 1; //生成一个(0~99)+1的随机数
//添加时间随机数
//srand((unsigned int)time(NULL));
int num;
cout << "b=" << b << endl;
cin >> num;
while (num != b)
{
cout << "很遗憾你猜错了,请重新输入" << endl;
if (num > b)
{
cout << "猜测过大" << endl;
}
else
{
cout << "猜测过小"<
cin >> num;
}
cout << "恭喜你猜对了" << endl;
system("pause");
return 0;
}
do while循环语句
#include
using namespace std;
int main32()
{
//do while语句
int a = 0;
do
{
cout << a << endl;
a++;
} while (a < 10);
//do while 和while的区别是do while会先执行循环语句再进行判断。
//求出三位数中的所有水仙花数(一个三位数,每个位上的数字的三次幂之和等于它本身)
int num = 100;
int A, B, C;
do
{
A = num % 10;
B = (num / 10) % 10;
C = num / 100;
if (A * A * A + B * B * B + C * C * C == num)
{
cout << num << "是水仙花数" << endl;
}
num++;
} while (num < 1000);
system("pause");
return 0;
}
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