三目运算符:C语言中唯一的一个,也称为问号表达式 a>b ? 1 : 0

由条件运算符组成条件表达式的一般形式为:

表达式1? 表达式2: 表达式3

sizeof是C语言的一种单目操作符,如C语言的其他操作符++、--等。sizeof操作符以字节形式给 出了其操作数的存储大小。

1)用于数据类型

2)用于常量(可以省略括号)

3)用于变量(可以省略括号)

创建源文件：msizeof_operator.c ，其代码如下:

#include <stdio.h>

void main() {

int a = 4;

short b;

double c;

int* ptr; /* example of sizeof operator */

printf("Line 1 - Size of variable a = %d\n", sizeof(a));

printf("Line 2 - Size of variable b = %d\n", sizeof(b));

printf("Line 3 - Size of variable c= %d\n", sizeof(c)); /* example of & and * operators */

ptr = &a; /* 'ptr' now contains the address of 'a'*/

printf("Line 4 - value of a is %d\n", a);

printf("Line 5 - *ptr is %d.\n", *ptr); /* example of ternary operator */

a = 10;

b = (a == 1) ? 20 : 30;

printf("Line 6 - Value of b is %d\n", b);

b = (a == 10) ? 20 : 30;

printf("Line 7 - Value of b is %d\n", b); }

执行代码，得到如下结果：

Line 1 - Size of variable a = 4

Line 2 - Size of variable b = 2

Line 3 - Size of variable c= 8

Line 4 - value of a is 4

Line 5 - *ptr is 4.

Line 6 - Value of b is 30

Line 7 - Value of b is 20