C 基本类型

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基本类型

void 类型

类型说明符 void 表示没有可用的值。它用于三种情况

1. 函数返回值类型 例如 void exit(int status);
2. 函数参数类型 例如 int rand(void);
3. 指针指向的类型 例如 void *malloc(size_t size);

C类型修饰符

修改符影响最小取值范围

C类型空间占用和取值范围

C语言标准只规定了每种数据类型都要覆盖一个确定的最小取值范围，没有定义它们各占多少字节。

要在特定平台上获取类型或变量的确切大小，可以使用 sizeof 运算符。表达式 sizeof(type) 产生对象或类型的存储大小（以字节为单位）。

在头文件中预定义了与具体实现相关的最小取值范围

• <limits.h> 定义了一些表示整型大小的常量。
• <float.h> 定义了与浮点算术运算相关的常量。

常用类型存储大小

/* data_types.c */

#include <stdio.h>

int main() {
    int a;
    char b;
    float c;
    double d;
    short int e;
    long int f;
    long long int g;
    unsigned int h;
    unsigned long int i;
    unsigned long long int j;
    signed char k;
    unsigned char l;
    long double m;

    short x_short;
    long x_long;
    long long x_long_long;

    printf("size of int = %lu bytes\n", sizeof(a));
    printf("size of char = %lu bytes\n", sizeof(b));
    printf("size of float = %lu bytes\n", sizeof(c));
    printf("size of double = %lu bytes\n", sizeof(d));
    printf("size of short int = %lu bytes\n", sizeof(e));
    printf("size of long int = %lu bytes\n", sizeof(f));
    printf("size of long long int = %lu bytes\n", sizeof(g));
    printf("size of unsigned int = %lu bytes\n", sizeof(h));
    printf("size of unsigned long int = %lu bytes\n", sizeof(i));
    printf("size of unsigned long long int = %lu bytes\n", sizeof(j));
    printf("size of signed char = %lu bytes\n", sizeof(k));
    printf("size of unsigned char = %lu bytes\n", sizeof(l));
    printf("size of long double = %lu bytes\n\n", sizeof(m));
    printf("size of short = %lu bytes\n", sizeof(x_short));
    printf("size of long = %lu bytes\n", sizeof(x_long));
    printf("size of long long = %lu bytes\n", sizeof(x_long_long));

    return 0;
}

编译：

cc  var.c  -o var

输出：

size of int = 4 bytes
size of char = 1 bytes
size of float = 4 bytes
size of double = 8 bytes
size of short int = 2 bytes
size of long int = 8 bytes
size of long long int = 8 bytes
size of unsigned int = 4 bytes
size of unsigned long int = 8 bytes
size of unsigned long long int = 8 bytes
size of signed char = 1 bytes
size of unsigned char = 1 bytes
size of long double = 16 bytes

size of short = 2 bytes
size of long = 8 bytes
size of long long = 8 bytes

更新于2022年04月06日