Explain C language 10 in detail (C language series)

Catalog

Preface ：

The operator ：

Arithmetic operators ：

Shift operator ：

Bit operators ： 

Assignment operator ：

Monocular operators ：

Relational operator ：

Logical operators ：

Conditional operators ：

Comma expression ：

Subscript reference operator ：

Function call operator ：

Structure member access operator ： 

Expression evaluation ： 

1. Implicit type conversion ：

2. Arithmetic conversion ：

3. Operator properties ：

Conclusion ：

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Preface ：

In the beginning C The language editor shared some small knowledge about operators with you and learned about operators , Next, I'll take you to learn more about operators and appreciate different operators .

The operator ：

Arithmetic operators ：

Arithmetic operators have ：/、-、+、*、%

1.% : among % Operands at both ends must be integer .

2. / : When calculating, if both ends are integers, only the integer part will be retained in the calculation result , If one of the two ends is a floating-point type, the result of the calculation is a floating-point type .（ As shown in the following code ）

Code ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	float a = 6 / 5;
	float b = 6.0 / 5;
	float c = 6 / 5.0;
	printf("%f\n", a);
	printf("%f\n", b);
	printf("%f\n", c);
	return 0;
}

Code screenshot ：

Shift operator ：

Shift operator ：<< 、>>

<<: Move left

characteristic ： The one on the left is discarded , The right to repair 0.

Code ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 2;
	int b = a << 1;
	printf("%d\n", a);// remain unchanged                  - 2
	printf("%d\n", b);// take a Move the binary bit of one bit to the left   - 4
	return 0;
}

Code screenshot ：

Analysis diagram ：

 

 

>>: Move right

There is a difference between moving right and moving left , There are two ways to shift right ：

1. Count right ： On the right side of the discarded , Left complement sign bit .

2. Logical shift right ： On the right side of the discarded , Left complement 0.

 

 

Bit operators ： 

Bit operators have ：&、|、^  

Be careful ： The operand of a bitwise operator must be an integer

&： Bitwise AND （ And by bits ）

example ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 3;
	int b = 5;
	int c = a & b;
	printf("%d\n", c);// 1
	return 0;
}

The resolution is as follows ： 

 

|： Press bit or （ To operate on or by bits ）

example ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 3;
	int b = 5;
	int c = a | b;
	printf("%d\n", c);// 7
	return 0;
}

The resolution is as follows ：

^: Bitwise XOR

The rules ： Same as 0, Different for 1.

example ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 3;
	int b = 5;
	int c = a ^ b;
	printf("%d\n", c);// 6
	return 0;
}

The resolution is as follows ： 

Assignment operator ：

  Assignment operators have ：=、+=、*=、/=、>>=、<<=、%=

Be careful ：= Is to assign values ,== It's judgment .

Monocular operators ：

Monocular operators have ：！、-、+、&、sizeof、~、--、++、*、（ type ）

！： Logical inverse operator

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int flage = 0;
	if (flage)//flage Print when true haha
		printf("haha\n");
	if (!flage)//flage Print when false xixi
		printf("xixi\n");
	return 0;
}

The code runs as follows ：

sizeof： Calculates the type length of the operand （ In bytes ）

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	short a = 0;
	int b = 0;
	int arr1[10] = { 0 };
	char arr2[10] = { 0 };
	printf("%d\n", sizeof(a));
	printf("%d\n", sizeof a);// Parentheses can be omitted when calculating as variable names 
	printf("%d\n", sizeof(int));// Do not omit parentheses when calculating as keywords 
	printf("%d\n", sizeof(b));
	printf("%d\n", sizeof(arr1));// You can calculate the size of the array 
	printf("%d\n", sizeof(arr2));
	return 0;
}

The code screenshot is as follows ：

~： The binary bit of a number is reversed bit by bit

&： Take the address operator

*： Dereference operator

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 4;
	int* pa = &a;//*--- explain pa It's a pointer variable 
	*pa = 10;//*-- Yes pa Quoting 
	printf("%d\n", a);
	return 0;
}

The code screenshot is as follows ：

( type )： Cast  

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = (int)3.14;
	printf("%d\n", a);
	return 0;
}

The code screenshot is as follows ：

 

Relational operator ： 

Relational operators have ：>、>=、<、<=、!=、==

 

Logical operators ：

Logical operators have ：&&、||

&&： Logic and

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 2;
	int b = 0;
	if (a && b)// False, false 
	{
		printf("haha\n");
	}
	else
	{
		printf("xixi\n");
	}
	return 0;
}

The code screenshot is as follows ：

||： Logic or

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 2;
	int b = 0;
	if (a || b)// There are really true 
	{
		printf("haha\n");
	}
	else
	{
		printf("xixi\n");
	}
	return 0;
}

The code screenshot is as follows ：
 

Be careful ：

1.&&： If one is 0 Then the following expressions do not need to be calculated .

2.||： If one is 1 Then the following expressions do not need to be calculated .

example ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int i = 0, a = 0, b = 2, c = 3, d = 4;
	//1.&&
	i = a++ && ++b && d++;
	printf("a = %d\nb = %d\nc = %d\nd = %d\n", a, b, c, d);

	//2.||
	//i = a++ || ++b || d++;
	//printf("a = %d\nb = %d\nc = %d\nd = %d\n", a, b, c, d);

	return 0;
}

among 1.&&  The running results of are as follows ：
2.|| The running results of are as follows ：

 

Conditional operators ：

The conditional operator is also called the trinocular operator ,（exp1？exp2：exp3）

if exp1 If yes, the calculation result is exp2 Otherwise, the value of exp3 Value .

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
// Use the conditional operator to calculate the maximum value 
int main()
{
	int a = 4;
	int b = 7;
	int max = (a > b ? a : b);
	printf("max = %d\n", max);
	return 0;
}

The code screenshot is as follows ：

 

Comma expression ：

（exp1,exp2,exp3,……,expn）

The value of the comma expression is expn Value .

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int a = 3;
	int b = 4;
	int c = 5;
	int d = (a++, c = a + b, b = a + c);
	printf("d = %d\n", d);// The result of the calculation is b Value 
	return 0;
}

The code screenshot is as follows ：

 

Subscript reference operator ：

[ ]: Examples are as follows .

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int arr[5] = { 1,2,3,4,5 };
	printf("%d\n", arr[3]);// among [] Reference operator for subscript 
	return 0;
}

The screenshot of the code running is as follows ：

 

Function call operator ：

（）： Examples are as follows .

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int Add(int x, int y)
{
	return x + y;
}
int main()
{
	int a = 2;
	int b = 3;
	int ret = Add(a, b);// among （） Call the operator for the function 
	printf("ret = %d\n", ret);
	return 0;
}

 

The screenshot of the code running is as follows ：
 

Structure member access operator ： 

The structure member access operators are ：.、->

The code is as follows ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
struct Book
{
	char name[10];
	char id[10];
	int price;
};
int main()
{
	struct Book b = {"C Language ","0x0060",30};
	struct Book* pb = &b;
	// adopt . Operator to access 
	printf("%s\n", b.name);
	printf("%s\n", b.id);
	printf("%d\n", b.price);

	printf("%s\n", (*pb).name);
	printf("%s\n", (*pb).id);
	printf("%d\n", (*pb).price);

	// adopt -> To visit 
	printf("%s\n", pb->name);
	printf("%s\n", pb->id);
	printf("%d\n", pb->price);
	return 0;
}

The code screenshot is as follows ：

Expression evaluation ： 

1. Implicit type conversion ：

Improve the overall shape ： Integer promotion is promoted according to the sign bit of variable type .

How should I fill the previous position when I am promoted ？ The rules are as follows .

Signed bit ：

         negative ： repair 1.

         Positive numbers ： repair 0.

Unsigned bit ： High direct compensation 0.

example ：

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	char a = 3;
	char b = 127;
	char c = a + b;
	printf("%d\n", c);
	return 0;
}

Screenshot of code running ：

The analysis is shown in the figure below ：

 

2. Arithmetic conversion ：

To byte long , High precision conversion .

3. Operator properties ：

influence ：

①： The priority of the operator .

②： The associativity of operators .

③： Whether to control the order of evaluation .

summary ： Although we have the precedence of many operators , But the expression we write cannot determine the unique calculation path through the properties of the operator , So this expression is the problem expression .

Conclusion ：

This time I share with you C The operators we often see in languages , I hope that's helpful , Students who want to learn remember to pay attention to Xiaobian and study together ！ If there are any mistakes in the article, you are also welcome to point out the maze for Xiaobian in time （ I'd like to thank you guys first ！）