【C primer Plus】如何知道当前系统的指定类型的大小是多少？

# include<stdio.h>
int main()
{
    // c99 
    printf("Type int has a size of %zd bytes.\n", sizeof(int));
    printf("Type char has a size of %zd bytes.\n", sizeof(char));
    printf("Type long has a size of %zd bytes.\n", sizeof(long));
    printf("Type long long has a size of %zd bytes.\n", sizeof(long long));
    printf("Type double has a size of %zd bytes.\n", sizeof(double));
    printf("Type long double has a size of %zd bytes.\n", sizeof(long double));
    return 0;
}
Type int has a size of 4 bytes.
Type char has a size of 1 bytes.
Type long has a size of 4 bytes.
Type long long has a size of 8 bytes.
Type double has a size of 8 bytes.
Type long double has a size of 16 bytes.

• long 类型和 int 类型大小一样；
• long long 类型和 double 类型大小一样；
• 别忘了 long double 是 double 长度两倍；