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检测scanf读取的值的变化

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对于作业，我们应该从文本文档中读取日期列表和相关值（温度） . 每行中的值用逗号分隔 .

示例数据：

dd,mm,yyyy,x,y,z,w
01,01,2011,1.1,5.2,6.5,7.5
02,01,2011,2.1,5.2,6.1,1.1
03,01,2011,4.5,2.5,6.1,2.1
...
30,01,2011,4.1,6.1,6.1,2.1
01,02,2011,2.5,6.1,7.1,6.3

到目前为止，我已经实现了一个循环来读取每一行：

while(scanf("%d,%d,%d,%f,%f,%f,%f", &dd, &mm, &yyyy, &x, &y, &z, &w) == 7)
{
}

我们假设文档中没有错误，没有重复日期 .

但是，可能缺少条目（不是每个月都有完整的数据;缺少天数） .

我无法检测每个月的数据（mm）是完整月份还是仅部分月份 .

例如：2011年3月31天 . 如果我从3月份开始有31个参赛作品，我需要打印“完整月份”，否则如果缺少日期我必须打印“部分月份” .

到目前为止，我一直在使用 if(mm==1){} 语句将 while(scanf(...)) 循环中的每个月分开，然后在单独的变量中递增它们，然后将它与整月的天数进行比较，但我不知道如何实现它以便它检测到该mm已从上一行（新月）更改并执行某项操作（例如：计算）

对不起，如果这令人困惑！

我们还没有教过数组，只有操作，循环和函数 .

c if-statement while-loop text-files scanf

3 回答

  • 0

    在某处保持上个月的 Value ;完成月度相关计算并在您阅读的月份高于上个月时重置月度计数器

    int curmonth = 1;
int dd,mm,yyy;
float x,y,z,w;
float xtotal = 0,ytotal = 0,ztotal = 0,wtotal = 0;
while(scanf("%d,%d,%d,%f,%f,%f,%f", &dd, &mm, &yyyy, &x, &y, &z, &w))==7 {
    if (mm == curmonth) {
        //add to current counters
        ztotal+=z;
        ytotal+=y;
        xtotal+=y;
        wtotal+=w;
    } else {
        if (mm < curmonth) 
            //not the expected order as per specs so better die now
            exit(1);
        printf("month=%d,my_calculations=%f,%f,%f,%f\n",xtotal,ytotal,ztotal,wtotal);
        xtotal = ytotal = ztotal = wtotal = 0; curmonth=mm;
    }
}
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  • 0

    首先，我不认为你想要不同月份的“单独变量” . 为什么不是按月索引的数组（即mm）？这可能会使您的代码长度减少一个数量级 . 哦，你还没有被教过阵列 .

    其次，在循环的顶部设置'last_mm'变量 . 这将是您上次循环时的mm值 . 将其初始化为-1或其他内容 . 当last_mm和mm不同时，您知道月份已更改 . 在循环的底部，将last_mm设置为mm .

    通常，这是在循环期间检测更改的方法 .

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  • 2

    以下代码未经测试，但是这样的事情应该可以为您提供没有数组的技巧 . 我希望你知道开关/箱子 .

    //Keep track of which month we are fetching data for
int currentMonth = 1;
//Number of days for which data have been read for the current month
int numberOfDaysInCurrentMonth = 0;
//Full = 1 would represent if all data is available for currentMonth
int full = 0;
//This is set to 1 only when data is read for a month different to currentMonth
int monthChanged = 0;

while(scanf("%d,%d,%d,%f,%f,%f,%f", &dd, &mm, &yyyy, &x, &y, &z, &w) == 7)
{
    // If month changed in last iteration  
    if(monthChanged == 1) {
        //Check if full = 1 print "Full Month" to output
        if(full == 1) {
             printf("Full Month");
        //Else there was partial data 
        } else {
             printf("Partial Month");
        }

        //Once the output is on the screen set this back to 0, so it will be set to 
        //1 only when month changes next time.
        monthChanged = 0;
    }

    //If currentMonth is the same as mm, just add 1 to number of days in this month
    //for which data is provided  
    if(currentMonth == mm) {
        ++numberOfDaysInCurrentMonth;

    //otherwise
    } else { 
        switch(currentMonth) {
            //In case the month is January, March, May, July, August, October, December
            case 1, 3, 5, 7, 8, 10, 12:
                //Number of days should be 31 for full to be 1
                if(numberOfDaysInCurrentMonth == 31)
                     full = 1;
            break;
            //In case the month is February
            case 2:
                //Number of days should be 28 for month to be full 
                //(ignoring leap years)  
                if(numberOfDaysInCurrentMonth == 28)
                     full = 1;
            break;
            //In case the month is April, June, September, November
            case 4, 6, 9, 11:
                //Number of days should be 28 for month to be full 
                if(numberOfDaysInCurrentMonth == 30)
                     full = 1;
            break;     
        }
        //Now that we have set what we desired, set
        //currentMonth to mm 
        currentMonth = mm;
        //The month just changed, otherwise we would not have been in this part
        of the code
        monthChanged = 1;
        //Number of days in current month starts from 1
        numberOfDaysInCurrentMonth = 1;
    }

    //Do whatever you are doing with data here
}
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