版本号设计

/**
 * 比较版本号
    GNU版本号示例： 3.5.20.9527
        主版本号
        次版本号
        修正版本号
        编译版本号
 *
 * @param v1 第一个版本号
 * @param v2 第二个版本号
 *
 * @return 如果版本号相等，返回 0,
 *         如果第一个版本号低于第二个，返回 -1，否则返回 1.
 */
int compareVersion(const char *v1, const char *v2)
{
    assert(v1);
    assert(v2);
    const char *p_v1 = v1;
    const char *p_v2 = v2;
    while (*p_v1 && *p_v2) {
        char buf_v1[32] = {0};
        char buf_v2[32] = {0};
        char *i_v1 = strchr(p_v1, ‘.‘);
        char *i_v2 = strchr(p_v2, ‘.‘);
        if (!i_v1 || !i_v2) break;
        if (i_v1 != p_v1) {
            strncpy(buf_v1, p_v1, i_v1 - p_v1);
            p_v1 = i_v1;
        }
        else
            p_v1++;
        if (i_v2 != p_v2) {
            strncpy(buf_v2, p_v2, i_v2 - p_v2);
            p_v2 = i_v2;
        }
        else
            p_v2++;
        int order = atoi(buf_v1) - atoi(buf_v2);
        if (order != 0)
            return order < 0 ? -1 : 1;
    }
    double res = atof(p_v1) - atof(p_v2);
    if (res < 0) return -1;
    if (res > 0) return 1;
    return 0;
}
int main(int argc, char *argv[])
{
    assert(compare_version("2.2.1", "2.2.0") > 0);
    assert(compare_version("2.2.1", "2.1.9") > 0);
    assert(compare_version("2.2.1", "2.2.01") == 0);
    assert(compare_version("2.2.1", "2.2.1") == 0);
    assert(compare_version("2.2", "2.1.1") > 0);
    assert(compare_version("2.2", "2.2.1") < 0);
    assert(compare_version("2.2.3.1", "2.2.3.5") < 0);
    assert(compare_version("2.2.3.1", "2.2.3.0") > 0);
    assert(compare_version("2.2", "2.2.1.4.5") < 0);
    assert(compare_version("2.2.3.4", "2.2.4.4.5") < 0);
    assert(compare_version("2.2.3.4.5.6", "2.2.3.4.5.12") < 0);
    assert(compare_version("2.2.3.4.5.6", "2.2.2.4.5.12") > 0);
    assert(compare_version("3.0.0.1", "3.0.0.0.1") > 0);
    assert(compare_version("3.1", "3.1.") == 0);
    puts("test pass.");
}

#include <stdio.h>
#include <math.h>

int main() {
    double x=3.1415, intpart;  //为变量赋初值
    double fractpart = modf(x, &intpart);  //求3.1415的小数部分
    printf("intpart: %lf\nfractpart: %lf\n", intpart, fractpart);

    return 0;
}

运行结果：
intpart: 3.000000
fractpart: 0.141500