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C language learning journey [operator (incomplete version)]

2022-08-10 01:26:00 【51CTO】

1.1 算术操作符

除号

To print floating point,Requires float on the sign side,且数据类型为double或者float类型

int main()
{
	//int i = 7 / 3;
	//printf("%d", i); // 2

	double i = 7.0 / 3;
	printf("%lf", i); // 2.3333
	return 0;
}

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取模

//取模操作符 Both ends of must be integers

1.2 移位操作符

左移/右移操作符

Shift bits left/右移动 n位
right shift fill：Arithmetic right shift complements the original sign bit;Logical right shift complement0

int main()
{   
	//左移操作符
	int a = -2;
	int b =  a << 1;
	printf("%d\n", a); //a并没有改变 
	printf("%d\n", b); // -4
	//右移操作符
	int c = a >> 1;
	printf("%d\n", c); // -1
	return 0;
}

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原码 ----（符号位不变,其他位按位取反）----> 反码 ----（反码+1）---->补码

1.3 位操作符

& 按位与：同1则1,其余为0
| 按位或：有1则1 ,无1则0
^ 按位异或：相同为0, 相异为1
备注：Their operands must all be integers！

实例1.交换两个数

int main()
{
	int a = 3;
	int b = 5;
	a = a ^ b;
	b = a ^ b;
	a = a ^ b;
	printf("%d, %d", a, b);
	return 0;
} 

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总结：

a ^ a = 0
a ^ b ^ b = a

1.4 单目操作符

！逻辑取反
sizeof The expressions in it do not participate in the operation

#include <stdio.h>
int main()
{
	// A code run needs to go through the slave test.c 编译 --> 链接 --> 运行 test.exe
	short s = 5;
	int a = 0;
	printf("%d\n", sizeof(s = a + 2));  // sizeofThe parameters in are run during the compilation process
	printf("%d\n", s); // Actually it hasn't changeda+2的值
	return 0;
	//输出结果为 2 5
}

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