Question

如果我有文件包含学生分数例如这个文件

{ 
students scores :
100
90
83
70
}

我怎样才能读出分数的值而没有阅读＆＃34;学生分数：＆＃34; ???

mu代码已经可以了但是阅读价值的问题

这是我的代码

#include <stdio.h>

int main (void)
{
    FILE *infile;
    double score, sum=0, average;
    int count=0, input_status;

    infile = fopen("scores.txt", "r");
    input_status = fscanf(infile, "%lf", &score);
    while (input_status != EOF) 
    {
        printf("%.2f\n ", score);
        sum += score;
        count++;
        input_status = fscanf(infile, "%lf",  &score);
    }
    average = sum / count;

    printf("\nSum of the scores is %f\n", sum);
    printf("Average score is %.2f\n", average);
    fclose(infile);
    getch();
}

Answer 1

我看到的问题：

input_status = fscanf(infile, "%lf", &score);
while (input_status != EOF)

不对。如果读取不成功，则fscanf的返回值将为0，如果成功则返回1。

更重要的是，您需要添加代码，跳过所有内容，直到您希望看到数字的位置。

char line[100];
while ( fgets(line, 100, infile) != NULL )
{
  // If the line containing "students scores :"
  // is found, break from the while loop.
  if (strstr(line, "students scores :") != NULL )
  {
    break;
  }
}

然后，将读取数据的行的开头更改为：

input_status = fscanf(infile, "%lf", &score);
while (input_status == 1 )

Answer 2

这是解析文件的一种相当简单的方法。

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int main (void)
   {
   FILE *infile;
   char  lineBuf[255+1];
   double score, sum=0, average;
   int count=0;
   int fieldsParsed;

   infile = fopen("scores.txt", "r");

   /** Read a line from the file. **/
   while(fgets(lineBuf, sizeof(lineBuf), infile))
      {
      /** Is the first character of the line a digit? **/
      if(!isdigit(*lineBuf))
         continue;  /* It is not a digit.  Go get the next line. */

      /** Convert the number string (in lineBuf) to an integer (score). **/
      score=atof(lineBuf);
      printf("fields[%d] %.2f\n ", fieldsParsed, score);
      sum += score;
      count++;
      }

   average = sum / count;

   printf("\nSum of the scores is %f\n", sum);
   printf("Average score is %.2f\n", average);
   fclose(infile);
//   getch(); Non-portable
   return(0);
   }

Answer 3

使用fseek（）跳过前导字节到数字。

如何从c中的文件中读取特定值

3 个答案: