以下代码将字节数转换成字符串形式的尺寸描述

#include <stdio.h>

#include <stdlib.h>

#include <string.h>



#define SECTOR_SIZE_DEFAULT   512LL

#define KILOBYTE_SIZE 1000LL

#define MEGABYTE_SIZE 1000000LL

#define GIGABYTE_SIZE 1000000000LL

#define TERABYTE_SIZE 1000000000000LL

#define KIBIBYTE_SIZE 1024LL

#define MEBIBYTE_SIZE 1048576LL

#define GIBIBYTE_SIZE 1073741824LL

#define TEBIBYTE_SIZE 1099511627776LL



typedef enum

{

    BASE_BINARY,

    BASE_DECIMAL

} Base;



typedef enum {

    DIGIT_UNIT_BYTE,

    DIGIT_UNIT_KILOBYTE,

    DIGIT_UNIT_MEGABYTE,

    DIGIT_UNIT_GIGABYTE,

    DIGIT_UNIT_TERABYTE,

    DIGIT_UNIT_KIBIBYTE,

    DIGIT_UNIT_MEBIBYTE,

    DIGIT_UNIT_GIBIBYTE,

    DIGIT_UNIT_TEBIBYTE

} DigitUnit;



char *

unit_format_custom (long long n, DigitUnit unit)

{

    char *str = malloc(64);

    memset (str, 0, 64);

    float f;

    int len;

    char *suffix;

    

    switch (unit)

    {

    case DIGIT_UNIT_BYTE:

    {

        sprintf (str, "%lld%s", n, "B");

        break;

    }

    case DIGIT_UNIT_KILOBYTE:

    {

        f = (float) n / KILOBYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "K");

        break;

    }

    case DIGIT_UNIT_MEGABYTE:

    {

        f = (float) n / MEGABYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "M");

        break;

    }

    case DIGIT_UNIT_GIGABYTE:

    {

        f = (float) n / GIGABYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "G");

        break;

    }

    case DIGIT_UNIT_TERABYTE:

    {

        f = (float) n / TERABYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "T");

        break;

    }

    case DIGIT_UNIT_KIBIBYTE:

    {

        f = (float) n / KIBIBYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "Ki");

        break;

    }

    case DIGIT_UNIT_MEBIBYTE:

    {

        f = (float) n / MEBIBYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "Mi");

        break;

    }

    case DIGIT_UNIT_GIBIBYTE:

    {

        f = (float) n / GIBIBYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "Gi");

        break;

    }

    case DIGIT_UNIT_TEBIBYTE:

    {

        f = (float) n / TEBIBYTE_SIZE;

        sprintf (str, "%.1f", f);

        len = strlen(str);

        suffix = (*(str + (len - 1)) == '0') ? str + len - 2 : str + len;

        memset (suffix, 0, 2);

        sprintf (suffix, "%s", "Ti");

        break;

    }

    }



    return str;

}



static char *

unit_format (long long n, Base base)

{

    DigitUnit unit = DIGIT_UNIT_BYTE - 1;

    long long tmp = n;



    if (base == BASE_DECIMAL)

    {

        while (tmp > 0)

        {

            tmp /= 1000;

            unit++;

        }

    }

    else if (base == BASE_BINARY)

    {

        while (tmp > 0)

        {

            tmp /= 1024;

            unit++;

            if (unit == DIGIT_UNIT_KILOBYTE)

            {

                unit = DIGIT_UNIT_KIBIBYTE;

            }

        }

    }



    return unit_format_custom (n, unit);

}



int main(int argc, char **argv)

{

    printf ("%s\n", unit_format_custom (25678, DIGIT_UNIT_KILOBYTE));

    printf ("%s\n", unit_format (4096, BASE_BINARY));

    printf ("%s\n", unit_format (4096, BASE_DECIMAL));

    printf ("%s\n", unit_format (8192, BASE_BINARY));

    printf ("%s\n", unit_format (8192, BASE_DECIMAL));

    return 0;

}