#include <stdio.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 1099511627776LLtypedef 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;/* Inefficiently removes all spaces from a string, in-place. */static voidstrip_string (char* str){    int i;    for (i = 0; str[i] != 0; i++) {        if (isspace (str[i])) {            int j;            for (j = i + 1; str[j] != 0; j++)                str[j - 1] = str[j];        }    }}/* Find non-number suffix.  Eg: find_suffix("32Mb") returns a pointer to * "Mb". */static char*find_suffix (const char* str){    while (str[0] != 0 && (isdigit (str[0]) || strchr(",.-", str[0])))        str++;    return (char *) str;}static DigitUnitparse_unit_suffix (const char* suffix){    if (strlen (suffix) > 1 && tolower (suffix[1]) == ‘i‘) {        switch (tolower (suffix[0])) {            case ‘k‘: return DIGIT_UNIT_KIBIBYTE;            case ‘m‘: return DIGIT_UNIT_MEBIBYTE;            case ‘g‘: return DIGIT_UNIT_GIBIBYTE;            case ‘t‘: return DIGIT_UNIT_TEBIBYTE;        }    } else if (strlen (suffix) > 0) {        switch (tolower (suffix[0])) {            case ‘b‘: return DIGIT_UNIT_BYTE;            case ‘k‘: return DIGIT_UNIT_KILOBYTE;            case ‘m‘: return DIGIT_UNIT_MEGABYTE;            case ‘g‘: return DIGIT_UNIT_GIGABYTE;            case ‘t‘: return DIGIT_UNIT_TERABYTE;        }    }    return -1;}long long unit_parse (const char *str){    char *suffix;    long long byte = -1;    long long byte_block = 1;    strip_string (str);    suffix = find_suffix (str);    DigitUnit unit = parse_unit_suffix (suffix);    switch (unit) {    case DIGIT_UNIT_BYTE:        break;    case DIGIT_UNIT_KILOBYTE:        byte_block = KILOBYTE_SIZE;        break;    case DIGIT_UNIT_MEGABYTE:        byte_block = MEGABYTE_SIZE;        break;    case DIGIT_UNIT_GIGABYTE:        byte_block = GIGABYTE_SIZE;        break;    case DIGIT_UNIT_TERABYTE:        byte_block = TERABYTE_SIZE;        break;    case DIGIT_UNIT_KIBIBYTE:        byte_block = KIBIBYTE_SIZE;        break;    case DIGIT_UNIT_MEBIBYTE:        byte_block = MEBIBYTE_SIZE;        break;    case DIGIT_UNIT_GIBIBYTE:        byte_block = GIBIBYTE_SIZE;        break;    case DIGIT_UNIT_TEBIBYTE:        byte_block = TEBIBYTE_SIZE;        break;    }    double temp = 0;    if (sscanf (str, "%lf", &temp) == 1)        byte = temp * byte_block;    return byte;}int main(int argc, char **argv){    if (argc > 1)        printf ("%lld\n", unit_parse (argv[1]));}

以下代码将字符串形式的尺寸描述转换成字节数