sizeof

sizeof是C语言的关键字，返回数据类型长度

32位系统中返回值类型为 unsigned int

64位系统中返回值类型为 long unsigned int



#include<stdio>

int main(void){
    printf("char_size=%lu\n", sizeof(char));//32位系统中需改为%u
    printf("unsigned_char=%lu\n", sizeof(unsigned char));
    printf("signed_char=%lu\n", sizeof(signed char));

    printf("\n\n");
    printf("int_size=%lu\n", sizeof(int));
    printf("short_int_size=%lu\n", sizeof(short int));
    printf("long_int_size=%lu\n", sizeof(long int));
    printf("unsigned_long_size=%lu\n", sizeof(unsigned long));
    printf("float_size=%lu\n", sizeof(float));
    printf("double_size=%lu\n", sizeof(double));
    printf("long_double_size=%lu\n", sizeof(long double));
    return 0;
}

输出

//32位                                //64位
char_size=1                           char_size=1
unsigned_char=1                       unsigned_char=1
signed_char=1                         signed_char=1


int_size=4                            int_size=4
unsigned_int_size=4                   unsigned_int_size=4
short_int_size=2                      short_int_size=2
long_int_size=4                       long_int_size=8
unsigned_long_size=4                  unsigned_long_size=8
float_size=4                          float_size=4
double_size=8                         double_size=8
long_double_size=12                   long_double_size=16