初阶第五节-操作符详解
1.算数操作符
#include
int main()
{
int a = 6 / 5;
printf("%d\n", a);//1
float a = 6 / 5;
printf("%f\n", a);//1.000000
float a = 6.0 / 5.0;//6/5.0
printf("%f\n", a);//1.200000
int a = 7 % 3;//取模操作符的两端必须是整数
printf("%d\n", a);//1
return 0;
} 2.移位操作符
//16进制
//0-9 10-15
//0-9 a-f
//10进制
//0-9
//8进制
//0-7
//2进制
//0-1
//整数的二进制表示有3种
//原码 反码 补码
//正整数的原码、反码、补码相同
//负整数的原码、反码、补码需要计算
//7符号位为0
//00000000000000000000000000000111 - 原码
//00000000000000000000000000000111 - 反码
//00000000000000000000000000000111 - 补码
//-7符号位为1
//10000000000000000000000000000111 - 原码
//11111111111111111111111111111000 - 反码(原码的符号位不变，其它位按位取反)
//11111111111111111111111111111001 - 补码(反码+1)
//整数在内存中存储的是补码2.1左移操作符
#includeint main() { int a1 = 7; int a2 = -7; //把a的二进制位向左移动一位 int b1 = a1 << 1; int b2 = a2 << 1; printf("a1 = %d\n", a1);//a = 7 printf("b1 = %d\n", b1);//b = 14 printf("a2 = %d\n", a2);//a = -7 printf("b2 = %d\n", b2);//b = -14 return 0; }
2.2右移操作符
#includeint main() { int a1 = 7; int a2 = -7; //把a的二进制位向右移动一位 int b1 = a1 >> 1; int b2 = a2 >> 1; printf("a1 = %d\n", a1);//a = 7 printf("b1 = %d\n", b1);//b = 3 printf("a2 = %d\n", a2);//a = -7 printf("b2 = %d\n", b2);//b = -4 return 0; }
3.位操作符
#include
int main()
{
int a = 3;
int b = -5;
//& - 按(2进制)位与
int c = a & b;
printf("c = %d\n", c);//3
//%d 意味着打印一个有符号的整数
//00000000000000000000000000000011 - 3的补码
//10000000000000000000000000000101 - -5的原码
//11111111111111111111111111111010 - -5的反码
//11111111111111111111111111111011 - -5的补码
//00000000000000000000000000000011 - 3的补码
//00000000000000000000000000000011 - a & b(二进制位相乘，只要有0则为0)
//| - 按(2进制)位或
int c = a | b;
printf("%d\n", c);//-5
//00000000000000000000000000000011 - 3的补码
//10000000000000000000000000000101 - -5的原码
//11111111111111111111111111111010 - -5的反码
//11111111111111111111111111111011 - -5的补码
//00000000000000000000000000000011 - 3的补码
//11111111111111111111111111111011 - a | b(只要有1则为1)
//11111111111111111111111111111010
//10000000000000000000000000000101 - 原码
//^ - 按(2进制)位异或
//对应的二进制位进行异或
//规则：相同为0，相异为1
int c = a ^ b;
printf("%d\n", c);//-8
//00000000000000000000000000000011 - 3的补码
//10000000000000000000000000000101 - -5的原码
//11111111111111111111111111111010 - -5的反码
//11111111111111111111111111111011 - -5的补码
//00000000000000000000000000000011 - 3的补码
//11111111111111111111111111111000 - a ^ b(相同为0，相异为1)
//11111111111111111111111111110111
//10000000000000000000000000001000 - 原码
return 0;
} 3.1例题
//不能创建临时变量(第三个变量)，实现两个数的交换
#include
int main()
{
int a = 3;
int b = 5;
//交换
//方法1
//3^3 = (011)^(011) = 0 -> a^a = 0
//0^3 = (000)^(011) = 3 -> 0^a = a
//异或操作符支持交换律
printf("a=%d b=%d\n", a, b);//a = 3 b = 5
a = a ^ b;//3^5
b = a ^ b;//3^5^5 = 3
a = a ^ b;//3^5^3 = 5
printf("a=%d b=%d\n", a, b);//a = 5 b = 3
//方法2
printf("a = %d b = %d\n", a, b);//a = 3 b = 5
//数值太大会溢出
a = a + b;//8
b = a - b;//3
a = a - b;//5
printf("a = %d b = %d\n", a, b);//a = 5 b = 3
//方法3
int c = 0;//空瓶
printf("a = %d b = %d\n", a, b);//a = 3 b = 5
c = a;
a = b;
b = c;
printf("a = %d b = %d\n", a, b);//a = 5 b = 3
return 0;
} //编写代码实现：求一个整数存储在内存中的二进制中1的个数
//求补码的二进制中1的个数
//int a = 3;
//a&1 可以求出a的第一位是否为1，然后将a右移一位
//00000000000000000000000000000011 - 3的补码
//00000000000000000000000000000001 - 1的补码
//00000000000000000000000000000001
//代码1
#include
int main()
{
int num = 10;
int count = 0;//计数
while (num)
{
if (num % 2 == 1)
count++;
num = num / 2;
}
printf("二进制中1的个数 = %d\n", count);//二进制中1的个数 = 2
return 0;
}
//代码2
#include
int main()
{
int num = -1;
int i = 0;
int count = 0;//计数
for (i = 0; i < 32; i++)
{
if (num & (1 << i))
count++;
}
printf("二进制中1的个数 = %d\n", count);//二进制中1的个数 = 32
return 0;
}
//代码3
#include
int main()
{
int num = -1;
int i = 0;
int count = 0;//计数
while (num)
{
count++;
num = num & (num - 1);
}
printf("二进制中1的个数 = %d\n", count);//二进制中1的个数 = 32
return 0;
} //如何改变二进制中第几位的数
#include
int main()
{
int a = 13;
//把a的二进制中的第5位置成1
a = a | (1 << 4);
printf("a = %d\n", a);//a = 29
//把a的二进制中的第5位置成0
a = a & ~(1 << 4);
printf("a = %d\n", a);//a = 13
//00000000000000000000000000001101 - 13的补码
//00000000000000000000000000010000 - 1<<4
//00000000000000000000000000011101 - 29的补码
//00000000000000000000000000011101 - 29的补码
//11111111111111111111111111101111 - ~(1<<4)
//00000000000000000000000000001101 - 13的补码
return 0;
} 4. 赋值操作符
//= -- 赋值
//== -- 判断
int weight = 120;//体重
weight = 89;//不满意就赋值
double salary = 10000.0;
salary = 20000.0;//使用赋值操作符赋值
//赋值操作符可以连续使用，比如：
int a = 10;
int x = 0;
int y = 20;
a = x = y+1;//连续赋值
//等价于
x = y+1;
a = x;4.1复合赋值符
| += | -= | *= |
| /= | %= | <<= |
| >>= | &= | |= |
| ^= |
#include
int main()
{
int a = 10;
a = a + 100;
a += 100;
a = a >> 3;
a >>= 3;
return 0;
} 5.单目操作符
5.1单目操作符介绍
// ! - 真的变成假，假的变成真
// C语言中，0表示假，非0表示真
#include
int main()
{
int flag = 0;
printf("%d\n", !flag);//1
//flag为真，打印hehe
if (flag) //0
{
printf("hehe\n");
}
//flag为假,打印haha
if (!flag) //1
{
printf("haha\n");//haha
}
return 0;
} //&操作符
#include
int main()
{
int a = 10;
printf("%p\n", &a);//a在内存中占了4个字节，&a取出的是a变量在内存中的起始地址
int* p = &a;//int* 是p的类型
return 0;
} //sizeof是一个操作符，不是函数
//计算的是变量所占内存空间的大小，单位是字节
//计算类型所创建的变量占据空间的大小，单位是字节
#include
int main()
{
short s = 5;
int a = 10;
printf("%d\n", sizeof(s = a + 2));//2
printf("%d\n", s);//5
printf("%d\n", sizeof(a));//4 - 计算a所占空间的大小，单位是字节
printf("%d\n", sizeof(int));//4
printf("%d\n", sizeof a);//4
int arr[10] = { 0 };
printf("%d\n", sizeof(arr));//40 - 计算的是整个数组的大小
printf("%d\n", sizeof(int [10]));//40 - int [10]是arr数组的类型
printf("%d\n", sizeof(arr[0]));//4 - 计算的是数组首元素的大小
int sz = sizeof(arr) / sizeof(arr[0]);
printf("%d\n", sz);//10 - 数组的元素个数
char arr2[] = "welcome to bit!!!!";//[welcome to bit!!!!\0]
int sz = sizeof(arr2) / sizeof(arr2[0]);
printf("%d\n", sz);//19 - 计算的时候包含了\0
char arr3[] = { 'a', 'b', 'c' };//abc
printf("%d\n", sizeof(arr3));//3
char ch[5] = { 'a', 'b', 'c' };//不完全初始化，剩余的默认为0
printf("%d\n", sizeof(ch));//5
return 0;
} //~操作符
#include
int main()
{
int a = 0;
//00000000000000000000000000000000 - 0的补码
//~ 按位取反
//11111111111111111111111111111111 - ~a
//11111111111111111111111111111110
//10000000000000000000000000000001 - 原码
int b = ~a;
printf("%d\n", a);//0
printf("%d\n", b);//-1
return 0;
} //++、--操作符(会改变原来的变量)
//代码1
#include
int main()
{
//前置、后置++
int a = 10;
int b = a++;//后置++，先使用，再++
//b=a；a=a+1；
printf("%d\n", b);//10
printf("%d\n", a);//11
int b = ++a;//前置++ - 先++，后使用
//b=a+1；a=a+1；
printf("%d\n", b);//11
printf("%d\n", a);//11
//前置、后置--
int a = 10;
int b = a--;//后置--，先使用，再--
//b=a；a=a-1；
printf("%d\n", b);//10
printf("%d\n", a);//9
int b = --a;//前置-- - 先--，后使用
//b=a-1；a=a-1；
printf("%d\n", b);//9
printf("%d\n", a);//9
return 0;
}
//代码2
#include
int main()
{
int a, b, c;
a = 5;
c = ++a; //c = 6, a = 6
b = ++c, c++, ++a, a++; //b = 7, c = 7, 8, a = 7, 8
b += a++ + c; //a++ + c = 16, b = 23, a = 9
printf("a = %d b = %d c = %d", a, b, c);//a = 9 b = 23 c = 8
return 0;
}
//*操作符 #includeint main() { int a = 10; printf("%p\n", &a);//& - 取地址操作符 int * pa = &a;//pa是用来存放地址的 - pa就是一个指针变量 *pa = 20;//* - 解引用操作符 - 间接访问操作符 printf("%d\n", a);//20 return 0; }
//(类型)强制类型转换
#include
int main()
{
int a = (int)3.14;//3.14默认为double类型，所以(int)3.14是将其强制类型转换为int类型
return 0;
}
6.关系操作符
#include
int main()
{
if (3 == 5)
{
}
if ("abc" == "abcdef")//err - 这样写是在比较2个字符串的首字符的地址
{
}
return 0;
} 7.逻辑操作符
//&& 看的是真假，表示的是并且
//|| 看的是真假，表示的是或者
#include
int main()
{
int a = 0;
int b = 5;
int c = a && b;
int d = a || b;
if (a && b) //a,b都为真才真
{
printf("%d\n", c);//0
printf("hehe\n");
}
if(a || b) //a,b只要有一个为真就为真
{
printf("%d\n", d);//1
printf("hehe\n");
}
return 0;
} 7.1例题
//总结：
//&& 左边为假，右边就不计算
//|| 左边为真，右边就不计算
//关键要看(a&&b)是否确定为真(或假)
#include
int main()
{
int i = 0, a = 0, b = 2, c = 3, d = 4;
i = a++ && ++b && d++;//a++是先使用，后++。则式子:(0 && ++b)肯定为假(=0)，所以++b不计算；且式子(0 && d++)肯定为假(=0)，所以d++不计算
printf("i = %d\na = %d\nb = %d\nc = %d\nd = %d\n", i, a, b, c, d);//0 1 2 3 4
int i = 0, a = 1, b = 2, c = 3, d = 4;
i = a++ && ++b && d++;//a++是先使用，后++。则式子:(1 && ++b)可能为真(=1)，++b计算；且式子:(1 && d++)可能为真(=1)，d++计算
printf("i = %d\na = %d\nb = %d\nc = %d\nd = %d\n", i, a, b, c, d);//1 2 3 3 5
int i = 0, a = 0, b = 2, c = 3, d = 4;
i = a++ || ++b || d++;//a++是先使用，后++。则式子:(0 || ++b)可能为真(=1)，所以++b计算；且式子(1 || d++)肯定为真(=1)，所以d++不计算
printf("i = %d\na = %d\nb = %d\nc = %d\nd = %d\n", i, a, b, c, d);//1 1 3 3 4
int i = 0, a = 1, b = 2, c = 3, d = 4;
i = a++ || ++b || d++;//a++是先使用，后++。则式子:(1 || ++b)肯定为真(=1)，所以++b不计算；且式子(1 || d++)肯定为真(=1)，所以d++不计算
printf("i = %d\na = %d\nb = %d\nc = %d\nd = %d\n", i, a, b, c, d);//1 2 2 3 4
return 0;
} 8.条件操作符
#include
int main()
{
int a = 3;
int b = 0;
if (a > 5)
b = 1;
else
b = -1;
//三目操作符
(a > 5) ? (b = 1) : (b = -1);
b = (a > 5 ? 1 : -1);
int max = (a > b ? a : b)；
return 0;
} 9.逗号表达式
#include
int main()
{
a = get_val();
count_val(a);
while (a > 0)
{
//业务处理
a = get_val();
count_val(a);
}
return 0;
}
//如果使用逗号表达式，改写：
#include
int main()
{
while (a = get_val(), count_val(a), a > 0)
{
//业务处理
}
return 0;
} #include
int main()
{
int a = 3;
int b = 5;
int c = 0;
//逗号表达式 - 要从做向右依次计算，但是整个表达式的结果是最后一个表达式的结果
int d = (c = 1, a = c + 3, b = a - 4, c += b);
//c=1 a=4 b=0 c=1
printf("%d\n", d);//1
return 0;
} 10.下标引用、函数调用和结构成员
10.1 [ ]下标引用操作符
#include
int main()
{
int arr[10] = { 0 };
//arr[7] -> *(arr+7) -> *(7+arr) -> 7[arr]
//arr是数组首元素的地址
//arr+7就是跳过7个元素，指向了第8个元素
//*(arr+7)就是第8个元素
printf("%d\n", arr[4]);
//[] - 就是下标引用操作符
//[] 的操作数是2个：arr , 4
arr[7] = 8;
7[arr] = 9;
return 0;
} 10.2 ( ) 函数调用操作符
接受一个或者多个操作数：第一个操作数是函数名，剩余的操作数就是传递给函数的参数。
//函数的定义
#include
int Add(int x, int y)
{
return x + y;
}
int main()
{
int a = 10;
int b = 20;
//函数调用
int ret = Add(a, b);//() - 函数调用操作符，操作数：Add,a,b
return 0;
} 10.3 访问一个结构的成员
//结构成员访问操作符
//.
//->
//结构体
//书：书名，书号，定价
//人：名字，年龄，性别
//创建了一个自定义的类型
#include
struct Book
{
//结构体的成员（变量）
char name[20];
char id[20];
int price;
};
int main()
{
//结构体变量名.成员名
struct Book b = {"C语言", "C20210509", 55};
struct Book * pb = &b;
//结构体指针->成员名
printf("书名：%s\n", pb->name);
printf("书号：%s\n", pb->id);
printf("定价：%d\n", pb->price);
printf("书名：%s\n", (*pb).name);
printf("书号：%s\n", (*pb).id);
printf("定价：%d\n", (*pb).price);
printf("书名：%s\n", b.name);
printf("书号：%s\n", b.id);
printf("定价：%d\n", b.price);
return 0;
} #includestruct Stu { char name[10]; int age; double score; }; void set_Stu(struct Stu* ps) { //strcpy((*ps).name, "zhangsan"); //(*ps).age = 20; //(*ps).score = 100.0; strcpy(ps->name, "zhangsan"); ps->age = 20; ps->score = 100.0; } void ptint_Stu(struct Stu* ps) { printf("%s %d %lf", ps->name, ps->age, ps->score); } int main() { struct Stu s = { 0 }; set_Stu(&s); ptint_Stu(&s);//zhangsan 20 100.000000 return 0; } 错误代码
11.表达式求值
11.1整型提升(类型小于int)
把整型放入char类型中时，先将其整型的原反补码列出来，然后进行截断。若以%d的形式打印出来，则整型提升时补符号位，但如果是unsigned char类型则需要补0，然后将其化为原码打印出来；若以%u的形式打印出来，则整型提升时补符号位，且打印时原反补码相同。
//char a = -1;//-1是整数，32个比特位
//10000000000000000000000000000001 - -1的原码
//11111111111111111111111111111110 - -1的反码
//11111111111111111111111111111111 - -1的补码
//11111111 - 截断
//11111111111111111111111111111111 - 整型提升
//int 4byte - 32bit
//char 1byte - 8bit
#include
int main()
{
char a = 5;
//00000000000000000000000000000101 - 5的补码
//00000011 - a
char b = 126;
//00000000000000000000000001111110 - 126的补码
//01111110 - b
char c = a + b;
//00000000000000000000000000000101 - a
//00000000000000000000000001111110 - b
//00000000000000000000000010000011
//10000011 - c
//11111111111111111111111110000011 - c的补码
//11111111111111111111111110000010 - c的反码
//10000000000000000000000001111101 - c的原码
printf("%d\n", c);//-125
return 0;
} //1.
//输出什么？
#include
int main()
{
char a = -1;
signed char b = -1;
//10000000000000000000000000000001 - -1的原码
//11111111111111111111111111111110 - -1的反码
//11111111111111111111111111111111 - -1的补码
//截断
//11111111 - a,b
//整型提升
//11111111111111111111111111111111
//10000000000000000000000000000000
//10000000000000000000000000000001 - -1的原码
unsigned char c = -1;
//无符号数进行整型提升，直接补0
//00000000000000000000000011111111 - 原反补码相同
//要以有符号整型的形式打印
printf("a = %d\nb = %d\nc = %d\n", a, b, c);//a = -1 b = -1 c = 255
return 0;
} //2.
#include
int main()
{
char a = -128;
//10000000000000000000000010000000
//11111111111111111111111101111111
//11111111111111111111111110000000
//截断
//10000000
//有符号数进行整型提升，补符号位
//11111111111111111111111110000000
//由于要以%u的形式打印，则无符号数的原反补码相同
unsigned char b = -128;
//截断后 - 10000000
//无符号数进行整型提升，直接补0
//00000000000000000000000010000000
//要以无符号整型的形式打印
printf("%u\n", a);//4294967168
printf("%u\n", b);//128
return 0;
} //3.
#include
int main()
{
char a = 128;
//00000000000000000000000010000000
//01111111111111111111111101111111
//01111111111111111111111110000000
//截断
//10000000
//有符号数进行整型提升，补符号位
//11111111111111111111111110000000
//由于要以%u的形式打印，则无符号数的原反补码相同
//要以无符号整型的形式打印
printf("%u\n", a);//4294967168
//截断后 - 10000000
//有符号数进行整型提升，补符号位
//11111111111111111111111110000000 - 补码
//10000000000000000000000001111111
//10000000000000000000000010000000 - 原码
//要以有符号整型的形式打印
printf("%d\n", a);//-128
return 0;
} //4.
#include
int main()
{
int i = -20;
unsigned int j = 10;
//10000000000000000000000000010100 - -20的原码
//11111111111111111111111111101011 - -20的反码
//11111111111111111111111111101100 - -20的补码
//+
//00000000000000000000000000001010 - 10的补码
//11111111111111111111111111110110
//10000000000000000000000000001001
//10000000000000000000000000001010 - -10的原码
printf("%d\n", i + j);//-10
//11111111111111111111111111110110 - 原反补码相同
printf("%u\n", i + j);//4294967286
return 0;
} #include
int main()
{
char a = 0xb6;//10110110 - 类型改为unsigned char高位补0才会输出a
short b = 0xb600;
int c = 0xb6000000;
if (a == 0xb6)
printf("a");
if (b == 0xb600)
printf("b");
if (c == 0xb6000000)
printf("c");//c
return 0;
}
#include
int main()
{
char c = 1;
printf("%zu\n", sizeof(c));//1
printf("%zu\n", sizeof(+c));//4
printf("%zu\n", sizeof(-c));//4
printf("%zu\n", sizeof(!c));//4 gcc - 4
return 0;
} 11.2算术转换(类型大于等于int)
12.操作符的属性
12.1问题表达式
13.练习
//写一个函数返回参数二进制中1的个数
//代码1
#include
int count_num_of_1(unsigned int n) //无符号整数，-1的符号位也被算作-1的大小
{
int count = 0;
while (n)
{
if ((n % 2) == 1)
{
count++;
}
n = n / 2;
}
return count;
}
//-1
//10000000000000000000000000000001
//11111111111111111111111111111110
//11111111111111111111111111111111
int main()
{
int num = 0;
scanf("%d", &num);
int n = count_num_of_1(num);
printf("%d\n", n);
return 0;
}
//代码2
#include
int count_num_of_1(int n)
{
int count = 0;
int i = 0;
for (i = 0; i < 32; i++)
{
if ((n >> i)&1 == 1)
{
count++;
}
}
return count;
}
int main()
{
int num = 0;
scanf("%d", &num);
int n = count_num_of_1(num);
printf("%d\n", n);
return 0;
}
//代码3
#include
int count_num_of_1(int n)
{
int count = 0;
while (n)
{
n = n & (n - 1);
count++;
}
return count;
}
//n = 15
//n = n&(n-1)
//1111 n
//1110 n-1
//1110 n
//1101 n-1
//1100 n
//1011 n-1
//1000 n
//0111 n-1
//0000 n
int main()
{
int num = 0;
scanf("%d", &num);
int n = count_num_of_1(num);
printf("%d\n", n);
return 0;
} //两个int(32位)整数m和n的二进制表达中，有多少位(bit)不同？
//代码1
#include
int count_diff_bit(int m, int n)
{
int count = 0;
int i = 0;
for (i = 0; i < 32; i++)
{
if (((m >> i) & 1) != ((n >> i) & 1))
{
count++;
}
}
return count;
}
int main()
{
int m = 0;
int n = 0;
scanf("%d %d", &m, &n);//1999 2299
int ret = count_diff_bit(m, n);
printf("%d\n", ret);//7
return 0;
}
//代码2
#include
int count_diff_bit(int m, int n)
{
int count = 0;
int ret = m ^ n;//^异或操作符，相同为0，相异为1
while (ret) //统计一下ret中二进制位有多少个1
{
ret = ret & (ret - 1);
count++;
}
return count;
}
int main()
{
int m = 0;
int n = 0;
scanf("%d %d", &m, &n);//1999 2299
int ret = count_diff_bit(m, n);
printf("%d\n", ret);//7
return 0;
} //获取一个整数二进制序列中所有的偶数位和奇数位，分别打印出二进制序列
//10
//00000000000000000000000000001010
#include
int main()
{
int i = 0;
int num = 0;
scanf("%d", &num);
//获取奇数位的数字
for (i = 30; i >= 0; i-=2)
{
printf("%d ", (num >> i) & 1);
}
printf("\n");
//获取偶数位的数字
for (i = 31; i >= 1; i -= 2)
{
printf("%d ", (num >> i) & 1);
}
return 0;
}
//多组输入，一个整数(2-20)，表示输出的行数，也表示组成"X"的反斜线和正斜线的长度
//针对每行的输入，输出用"*"组成的X形图案
#include
int main()
{
int n = 0;
while (scanf("%d", &n) == 1)//只有一个字符时，scanf读取成功返回1，n个字符返回n
{
int i = 0;
int j = 0;
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
{
if (i == j)
printf("*");
else if (i + j == n - 1)
printf("*");
else
printf(" ");
}
printf("\n");
}
}
return 0;
} //多组输入，一行有两个整数，分别表示年份和月份，用空格分隔
// 输出一个整数，表示这一年的这一个月有多少天
#include
int is_leap_year(int y)
{
return (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0));
}
int main()
{
int y = 0;
int m = 0;
int d = 0;
int days[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
while (scanf("%d%d", &y, &m) == 2)//只有一个字符时，scanf读取成功返回1，n个字符返回n
{
int d = days[m];
if ((is_leap_year(y) == 1) && (m == 2))//判断闰年2月
{
d++;
}
printf("%d\n", d);
}
return 0;
} //多组输入数据，每一行输入三个a,b,c(0
int main()
{
int a = 0;
int b = 0;
int c = 0;
while (scanf("%d %d %d", &a, &b, &c) == 3)//scanf的返回值取决于有几个字符
{
if ((a + b > c) && (a + c > b) && (b + c > a))//判断是否为三角形
{
if ((a == b) && (b == c))//等边
{
printf("Equilateral triangle!\n");
}
else if ((a == b, c != b) || (a == c, b != c) || (b == c, a != c))//等腰
{
printf("Isosceles triangle!\n");
}
else
printf("Ordinary triangle!\n");
}
else
printf("Not a triangle!\n");
}
return 0;
}
//输入一个整数n(0 <= n <=10^9)
//输出整数n的每位，如果是奇数，把它变成1；如果是偶数，把它变成0
#include
#include
int main()
{
int i = 0;
int sum = 0;
int n = 0;
scanf("%d", &n);
while (n)
{
int bit = n % 10;
if (bit % 2 == 1)//如果为奇数
{
bit = 1;
}
else //如果为偶数
{
bit = 0;
}
sum += bit * pow(10, i);
i++;
n /= 10;
}
printf("%d\n", sum);
return 0;
} #includeint main() { int a = 0; int b = 0; int c = 0; int d = 0; int e = 0; for (a = 1; a <= 5; a++) { for (b = 1; b <= 5; b++) { for (c = 1; c <= 5; c++) { for (d = 1; d <= 5; d++) { for (e = 1; e <= 5; e++) { if ( ((a == 3) + (b == 2) == 1) && ((b == 2) + (e == 4) == 1) && ((c == 1) + (d == 2) == 1) && ((c == 5) + (d == 3) == 1) && ((e == 4) + (a == 1) == 1)) { if (a * b * c * d * e == 120) { printf("a=%d b=%d c=%d d=%d e=%d\n", a, b, c, d, e); //a=3 b=1 c=5 d=2 e=4 } } } } } } } return 0; }
#includeint main() { int killer = 0; for (killer = 'a'; killer <= 'd'; killer++) { //判断 if ((killer != 'a') + (killer == 'c') + (killer == 'd') + (killer != 'd') == 3) { printf("%c\n", killer);//c } } return 0; }
