#include <stdio.h>
int main()
{
    puts("各种数据类型所占内存字节数\n\n");
    puts("integers:");
    printf("sizeof(char) = %d\n",sizeof(char));
    printf("sizeof(short int) = %d\n",sizeof(short));
    printf("sizeof(int) = %d\n",sizeof(int));
    printf("sizeof(unsigned int) = %d\n",sizeof(unsigned int));
    printf("sizeof(long int) = %d\n",sizeof(long));
    printf("sizeof(long long int) = %d\n",sizeof(long long ));

    puts("\nfloat:");
    printf("sizeof(float) = %d\n",sizeof(float));
    printf("sizeof(double) = %d\n",sizeof(double));
    printf("sizeof(long double) = %d\n",sizeof(long double));
    printf("\npointers:\n");
    printf("sizeof(char *) = %d\n",sizeof(char *));
    printf("sizeof(int *) = %d\n",sizeof(int *));
    printf("sizeof(float *) = %d\n",sizeof(float *));
    printf("sizeof(double *) = %d\n",sizeof(double *));
    //64 bit system
    return 0;    
}

【结果】

各种数据类型所占内存字节数


integers:
sizeof(char) = 1
sizeof(short int) = 2
sizeof(int) = 4
sizeof(unsigned int) = 4
sizeof(long int) = 8
sizeof(long long int) = 8

float:
sizeof(float) = 4
sizeof(double) = 8
sizeof(long double) = 16

pointers:
sizeof(char *) = 8
sizeof(int *) = 8
sizeof(float *) = 8
sizeof(double *) = 8