【C语言补漏】数据类型

数据类型 

变量在内存中所占坑的大小。

c语言下的数据类型

sizeof运算符

用于获得数据类型或表达式的长度

–sizeof(object);  //sizeof(对象);

–sizeof(type_name);  //sizeof(类型);

–sizeof object;  //sizeof 对象;

示例程序&＃xff1a;

#includevoid main()
{int i;char j;float k;i &＃61; 123;j &＃61; &＃39;c&＃39;;k &＃61; 3.14;printf("size of int is: %d\n", sizeof(int));printf("size of i is: %d\n", sizeof(i));printf("size of char is: %d\n", sizeof(char));printf("size of int j is: %d\n", sizeof(j));printf("size of float is: %d\n", sizeof(float));printf("size of k is: %d\n", sizeof(k));
}

运行结果&＃xff1a;

size of int is: 4
size of i is: 4
size of char is: 1
size of int j is: 1
size of float is: 4
size of k is: 4
请按任意键继续. . .

示例程序&＃xff1a;

#includevoid main()
{printf("size of int is: %d\n", sizeof(int));printf("size of short int is: %d\n", sizeof(short));printf("size of long int is: %d\n", sizeof(long));printf("size of long long int is: %d\n", sizeof(long long));printf("size of char is: %d\n", sizeof(char));printf("size of _Bool is: %d\n", sizeof(_Bool));printf("size of float is: %d\n", sizeof(float));printf("size of double is: %d\n", sizeof(double));printf("size of long double is: %d\n", sizeof(long double));
}

运行结果&＃xff1a;

size of int is: 4
size of short int is: 2
size of long int is: 4
size of long long int is: 8
size of char is: 1
size of _Bool is: 1
size of float is: 4
size of double is: 8
size of long double is: 8
请按任意键继续. . .

变量在不同编译环境、操作系统下&＃xff0c;占用的大小是不一样的&＃xff0c;但是一定保证&＃xff1a;

signed和unsigned 

限定变量的范围&＃xff0c;有符号和无符号。

•[signed] short [int]

•unsigned short [int]

•[signed] int

•unsigned int

•[signed] long [int]

•unsigned long [int]

•[signed] long long [int]

•unsigned long long [int]•

看看下面的程序&＃xff0c;运行结果会出现什么效果&＃xff1a;

#includevoid main()
{short i;unsigned short j;i &＃61; -1;j &＃61; -1;printf("i &＃61; %d\n", i);printf("j &＃61; %d\n", j);
}

运行结果&＃xff1a;

i &＃61; -1
j &＃61; 65535
请按任意键继续. . .

为什么会出现这样的结果&＃xff1f;&＃xff1f;&＃xff1f;是因为取值范围出现问题。 

unsigned short 类型的变量取值范围是&＃xff1a;0~65535

超出的取值范围&＃xff0c;所以。。。你懂得

★finished by songpl,2018.11.27