c语言实验

Posted 2022-11-12 一只小阿大:)

目录

• 运算符优先级
• 0.1+0.2二十位显示
• %-6f和%8f左右对齐
• 整形常量020和20打印
• 字符与字符串
• switch

由于快离职了，不给我安排活了，然后上班没事干看了看C陷阱与缺陷，好玩的我就写上来了

运算符优先级

#include "stdio.h"
#include "stdlib.h"
int main()

    int x = 3;
    int y = 5;

    printf("%d\\n",x---y);
    
    return 0;

Operation results:
-2

#include "stdio.h"
#include "stdlib.h"

int main()

	int x = 10;
	int y = 20;
	int *p = &x;
	printf("%f\\n",y/ *p);
	
	return 0;

Operation results:
0.000000
'/'和'*'挨着就是注释了,
打印变成%d结果就是2了，其实需要强转一下(float)(y/(*p))打印就是2.000000

0.1+0.2二十位显示

#include "stdio.h"
#include "stdlib.h"
int main()

    printf("%.20f\\n",0.1+0.2);
    
    return 0;

Operation results:
0.30000000000000004000

%-6f和%8f左右对齐

#include "stdio.h"
#include "stdlib.h"

int main()

	printf("%-6f\\n",0.1+0.2);
	printf("%8f\\n",0.1+0.2);
	
	return 0;

Operation results:
0.300000
0.300000

整形常量020和20打印

如果一个整形常量的第一个字符是数字0，那么该常量将被视作八进制数。

#include "stdio.h"
#include "stdlib.h"

int main()

	printf("%d\\n",20);
	printf("%d\\n",020);
	
	return 0;

Operation results:
20
16

字符与字符串

单引号引起的一个字符实际上代表一个整数

#include "stdio.h"
#include "stdlib.h"

int main()

	//这三种方式其实是等效的
	char hello[] = 'h','e','l','l','o',' ','w','o','r','l','d','\\n',0;
	printf("hello world\\n");
	printf(hello);
	printf("%s",hello);
	
	return 0;

Operation results:
hello world
hello world
hello world

switch

#include <stdio.h>
#include <string.h>

int main()
	switch (3)
	
		case 1:printf("one\\n");
		case 2:printf("two\\n");
		case 3:printf("three\\n");
		case 4:printf("four\\n");
		case 5:printf("five\\n");
	

	return 0;

Operation results:
three
four
five