c - 结构数组中的垃圾输出

Question

这是我在 sortstudents() 函数中的项目，当我尝试打印数组时，我尝试从文件中读取数据，数据位于一行或一行上，但我得到了垃圾数据

这是有关文件中数据的样子的示例(2 条记录):
1 穆罕默德塔拉特 €@A
2 艾哈迈德·穆罕默德@A

#include <stdio.h>
#include <string.h>
#include <conio.h>
#include <stdlib.h>
#include <windows.h>
///////////////////////////////////////////////////////////////////////////
struct student
 {
  char  id[5];
  char  name[30];
  int   term;
  float gpa;
  char  grade;
 };

struct student stu;

typedef struct student stud;


//////////////////////////////////////////////////////////////////////////
//set the cordinate to 0, 0 (top-left corner of window)
//<windows.h> is needed
COORD coord = {0,0};
//////////////////////////////////////////////////////////////////////////
//need cordinate struct to use it
//gotoxy to set coordinate x,y
void gotoxy(int x, int y)
{
//X and Y coordinates 
  coord.X = x; coord.Y = y;
// ew3a tensa Microsoft 
  SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}
//////////////////////////////////////////////////////////////////////////
//print regtangle shape Ascii table www.asciitable.com
// window width = 80 character window hight = 25 character
void drawRectangle()
{
 int i, j;
//print the corner rear top left 
 gotoxy(0,0);    
 printf("%c",201);
// print 78 line shape = starts from rear top left ended at the top rear right     
 for(i = 1; i < 78; i++)
  {
   gotoxy(i, 0);
   printf("%c",205);
  }
//print the corner rear top right
 gotoxy(78,0);    
 printf("%c",187);
//print the corner rear right side with width = 25
 for(i = 1; i < 25; i++)
  {
   gotoxy(78, i);
//print T-shape at width 6 and after 6 proceed until 25 printing right side 
   if(i == 6)
    {
     printf("%c",185);
    }
   else
    {
     printf("%c",186);
    }
  }
//print the corner rear bottom right
 gotoxy(78, 25);
 printf("%c",188);
// -i- already = 78
// print bottom side pf the regtangle
for(i = 77; i > 0; i--)
 {
  gotoxy(i,25);
// print T-shape at width 35 and after that proceed until 78 printing rgt base side 
 if(i == 35)
  {
   printf("%c",202);
  }
 else
  {
   printf("%c",205);
  }
 }
//print the corner rear bottom left
  gotoxy(0,25);
  printf("%c",200);
// print T-shape at width 6 and after 6 proceed until 25 printing left side     
 for(i = 24; i > 0; i--)
  {
   gotoxy(0,i);
   if(i == 6)
    {
     printf("%c",204);
    }
   else
    {
     printf("%c",186);
    }
   }
// print T-shape at width 36 and connect left side to right side
 for(i = 1; i < 78; i++)
  {
   gotoxy(i,6);
   if(i == 35)
    {
     printf("%c",203);
    }
    else
    {
     printf("%c",205);
    }
  }
// connect middle T-shape at the middle of the regtangle to the base
 for(i = 7; i < 25; i++)
  {
   gotoxy(35,i);
   printf("%c",186);
  }
}
//////////////////////////////////////////////////////////////////////////
// Build Program window interface using functions --drawRectangle 
// with color 1 = Blue & Font color 7 = White
void swindow()
{
 int i;
 drawRectangle();
 gotoxy(28,1);
 system("color 17");
 printf("STUDENT GRADE SYSTEM");
 gotoxy(28,2);
 for(i=1;i<21;i++)
 {
  printf("%c",205);
 }
 gotoxy(15,3);
 printf("College of Computing and Information Technology");
 gotoxy(10,4);
 printf(" ");
 gotoxy(10,5);
 printf("Arab Academy for Science, Technology & Maritime Transport");
 gotoxy(25,24);
}
//////////////////////////////////////////////////////////////////////////
void print_heading(const char st[])
{
 gotoxy(50,8);
 printf("%s",st);
}
//////////////////////////////////////////////////////////////////////////
void clearWindow()
{
    int i,j;
    for(i = 37; i < 78; i++)
     {
        for(j = 7; j < 25; j++)
        {
           gotoxy(i,j);
           printf(" ");
        }
    }
}
//////////////////////////////////////////////////////////////////////////



//////////////////////////////////////////////////////////////////////////
void add()
{
    clearWindow();
    print_heading("Add Record");
    int print = 37;
    char ans;
    int i;
    FILE *fp;
    fp = fopen("record.txt","ab+");
    if(fp == NULL)
    {
     MessageBox(0,"Error in Opening file\nMake sure your file is not write protected","Warning",0);
    }
    else
    {
     fflush(stdin);
//here i can Add  Records ... 
//////////////////////////////////////////////////////////////////////////////// 
     gotoxy(print,10);printf("ID: ");gets(stu.id);
     gotoxy(print,12);printf("Name: ");gets(stu.name);
     gotoxy(print,14);printf("Term: ");scanf("%d",&stu.term);
     gotoxy(print,16);printf("Score % : ");scanf("%f",&stu.gpa);

     if (stu.gpa>=3.40)
      {
       stu.grade='A';
      }
     else {
           if (stu.gpa>=2.80)
            {stu.grade='B';}
           else
           {
            if (stu.gpa>=2.20)
             {stu.grade='C';}
            else
            {
             if (stu.gpa>=2.00)
              {stu.grade='D';}
             else
             {stu.grade='F';}
             }
           }
          }
     gotoxy(print,18);printf("GPA: %c",stu.grade);printf("\n");

     gotoxy(print,20);printf("Press(Y) to Save (N) for Cancel... ");//scanf("%c",&ans);
     ans = getche();   

     if (ans=='y' || ans=='Y')
     {
      fwrite(&stu, sizeof(stu), 1, fp);
      gotoxy(40,22); printf("The record is sucessfully added");
     }
     else 
     {
      gotoxy(40,22); printf("Entry process cancelled");
     }
    }
    fclose(fp);
}
//////////////////////////////////////////////////////////////////////////
void search(){
    clearWindow();
    print_heading("Search Record");

    char s_id[5];

    int isFound = 0;

    gotoxy(37,10);

    printf("Enter ID to Search: ");

    fflush(stdin);

    gets(s_id);
 //Read the record file from File
    FILE *fp;
    fp = fopen("record.txt","ab+");
    while(fread(&stu,sizeof(stu),1,fp) == 1)
    {
        if(strcmp(s_id,stu.id) == 0)
        {
         isFound = 1;
         break;
        }
    }
    if(isFound == 1){
        gotoxy(37,12);printf("The record is Found");
        gotoxy(37,13);printf("--------------------");
        gotoxy(37,14);printf("ID: %s",stu.id);
        gotoxy(37,16);printf("Name: %s",stu.name);
        gotoxy(37,18);printf("Term: %d",stu.term);
        gotoxy(37,20);printf("Score %: %0.1f",stu.gpa);
        gotoxy(37,22);printf("GPA: %c",stu.grade);
    }else
    {
     gotoxy(37,12);printf("Sory, No record found in the database");
    }
    fclose(fp);
}
//////////////////////////////////////////////////////////////////////////
void sortstudents()
{
 clearWindow(); 
 FILE *fp;
    fp = fopen("record.txt","r");

//////// detect number of characters ////////
char nextChar = getc(fp);
int numCharacters = 0;

while (nextChar != EOF)
{
    //Do something else, like collect statistics
    numCharacters++;
    nextChar = getc(fp);
}
//////// detect number of characters ////////

int chunck = numCharacters/sizeof(stu);

//stud *arr = (stud *)malloc(chunck);
stud starray[25];

int d;

int numStudents = 0;

     while( fscanf(fp,"%s%s%d%f%c",stu.id,stu.name,&stu.term,&stu.gpa,&stu.grade) > 0)
    {
          starray[numStudents++] = stu;
    }

  gotoxy(37,12);printf("The record is Found");
  gotoxy(37,13);printf("--------------------");
  gotoxy(37,14);printf("ID: %s",starray[0].id);
  gotoxy(37,16);printf("Name: %s",starray[0].name);
  gotoxy(37,18);printf("Term: %d",starray[0].term);
  gotoxy(37,20);printf("Score %: %0.1f",starray[0].gpa);
  gotoxy(37,22);printf("GPA: %c",starray[0].grade);


     /*"ID: %s",stu.id);
     "Name: %s",stu.name);
     "Term: %d",stu.term);
     Score %: %0.1f",stu.gpa);
     "GPA: %c",stu.grade);*/            

fclose(fp);

}
//////////////////////////////////////////////////////////////////////////
void menu(){
    int choice;
    int x = 2;
    while(1)
    {
     gotoxy(x,10);
     printf("1. Add Student");
     gotoxy(x,12);
     printf("2. Search Student");
     gotoxy(x,14);
     printf("3. Statistics");
     gotoxy(x,16);
     printf("4. Close");
     gotoxy(x,20);
     printf("Please enter your choice :");
     scanf("%d",&choice);

    switch(choice)
     {
      case 1:
       add();
      break;

      case 2:
       search();
      break;

      case 3:
       sortstudents();
      break;

      case 4:
       exit(0);
      break;

      default:
       break;
        }
    }
}
//////////////////////////////////////////////////////////////////////////
int main()
{
// draw entry window
//drawRectangle();
swindow();
menu();
//clearWindow();
 system("PAUSE");   
 return 0; 
}

Answer 1

在 sortStudents 中，开头有一个循环，它将读取文件中的所有字符。然后您尝试将文件作为一种记录来读取。当您尝试读取超出文件末尾的内容时，使用 fscanf 将返回 EOF。

即使您没有将任何记录读入您的starray数组，您仍然会打印starray[0]中的值，这将全部未初始化(因此包含不确定的(例如看似随机的)值)。