将proc/uptime转换为DD:HH:MM:SS

Question

我已经读取了/proc/uptime的值(这是上次引导后的秒数)，我正在尝试将其转换为: DD:HH:MM:SS。我不断地得到这样的错误：“作为赋值的左操作数所需的lvalue：*

这是我的密码：

​

/**
* Method Retrieves Time Since System Was Last Booted [dd:hh:mm:ss]
*/
int kerstat_get_boot_info(sys_uptime_info *s)
{
    /* Initialize Values To Zero's */
    memset(s, 0, sizeof(sys_uptime_info));

    /* Open File & Test For Failure */
    FILE *fp = fopen("/proc/uptime", "r");
    if(!fp) { return -1; }

    /* Intilaize Variables */
    char buf[256];
    size_t bytes_read;

    /* Read Entire File Into Buffer */
    bytes_read = fread(buf, 1, sizeof(buf), fp);

    /* Close File */
    fclose(fp);

    /* Test If Read Failed Or If Buffer Isn't Big Enough */
    if(bytes_read == 0 || bytes_read == sizeof(buf))
        return -1;

    /* Null Terminate Text */
    buf[bytes_read] = '\0';

    sscanf(buf, "%d", &s->boot_time);

    &s->t_days = s->boot_time/60/60/24;
    &s->t_hours = s->boot_time/60/60%24;
    &s->t_minutes = s->boot_time/60%60;
    &s->t_seconds = s->boot_time%60;
}

​

我的结构是这样的：

​

typedef struct {

    /* Amount of Time Since Last Boot [dd:hh:mm:ss] */
    /* Time When System Was Last Booted */
    int boot_time;
    int t_days;
    int t_hours;
    int t_minutes;
    int t_seconds;

} sys_uptime_info;

​

我不喜欢使用int，因为在这种情况下没有意义.我尝试过double和float，但是当我这样做时，我很难从buf读取值到boot_time。非常感谢您的帮助！

Answer 1

这是你的问题

&s->t_days = s->boot_time/60/60/24;
&s->t_hours = s->boot_time/60/60%24;
&s->t_minutes = s->boot_time/60%60;
&s->t_seconds = s->boot_time%60;

变到

s->t_days = s->boot_time/60/60/24;
s->t_hours = s->boot_time/60/60%24;
s->t_minutes = s->boot_time/60%60;
s->t_seconds = s->boot_time%60;

当您看到错误：“作为赋值的左操作数所需的lvalue时，首先要检查的是每个赋值的左手侧。lvalue应该始终解析为内存地址。变量名称是lvalue，可以将其比作对象。s->t_day是一个可分配值的lvalue，它可以被分配为一个不相同的值&s->t_days.lvalue，因为它们可以出现在分配的左边。rvalue是可以出现在右边的值。在这种情况下，赋值操作符的左边有一个rvalue。