# include 
#include 
Typedef struct 
{
Long ID, Class, Date; 
Char Name [20]. 
Char gender [20]. 
Int Chinese, math, English, total; 
} student; 
Student s [2000]; 
Int num=0; 
Void the add () 
{
Char ch, k [80]; 
The FILE * fp. 
Fp=fopen (" sudent. TXT ", "a +"); 
if(! Fp) 
{
Printf (" file connot be the opened "); 
exit(1); 
} 
Printf (" input student data \ n "); 
While (1) 
{
Printf (" student id \ n "); 
Gets (k); 
S [num] ID=atol (k); 
Printf (" name \ n "); 
Gets (s) [r]. Num Name); 
Printf (" gender \ n "); 
Gets (s) [r]. Num gender); 
Printf (" class \ n "); 
Gets (k); 
S [num]. Class=atol (k); 
num++; 
Fwrite (& amp; S (num), sizeof (s), num, fp); 
Printf (" another (y/n)?" ); 
ch=getchar(); 
If (ch=='n') 
break; 
Gets (k); 
The fflush (stdin); 
} 
fclose(fp); 
} 
Void main () 
{
The add (); 
} 

CodePudding user response:

num++;
Fwrite (& amp; S (num), sizeof (s), num, fp);

Should
Fwrite (& amp; S (num), sizeof (s), num, fp);
num++;
!

CodePudding user response:

Seems to be no effect

CodePudding user response:

Before each entry empty data?
You apply for the
Char Name [20].
Char gender [20].
Only 20 data area,
If not empty, inputting several times will be area of more than 20

CodePudding user response:

Your own Debug step through it and see, all the value of the parameter is correct?

CodePudding user response:

 
Typedef struct 
{
Long ID, Class, Date; 
Char Name [20]. 
Char gender [20]. 
Int Chinese, math, English, total; 
} student; 
Student s [2000]; 
Int num=0; 
Void the add () 
{
Char ch, k [80]; 
The FILE * fp. 
Fp=fopen (" sudent. TXT ", "a +"); 
if(! Fp) 
{
Printf (" file connot be the opened "); 
exit(1); 
} 
Printf (" input student data \ n "); 
While (1) 
{
Printf (" student id \ n "); 
Gets (k); 
S [num] ID=atol (k); 
Printf (" name \ n "); 
Gets (s) [r]. Num Name); 
Printf (" gender \ n "); 
Gets (s) [r]. Num gender); 
Printf (" class \ n "); 
Gets (k); 
S [num]. Class=atol (k); 
Fwrite (& amp; S (num), sizeof (student), num, fp); 
num++; 
Printf (" another (y/n)?" ); 
ch=getchar(); 
If (ch=='n') break; 
The fflush (stdin); 
} 
fclose(fp); 
} 
Void main () 
{
The add (); 
} 

Note that
fwrite (& amp; S (num), sizeof (student), num, fp);
num++;

CodePudding user response:

Int len=sizeof (s);//136000
Len=sizeof (student);//68
The word
Fwrite (& amp; S (num), sizeof (s), num + 1, fp);
Only the num==0

CodePudding user response:

Don't spill!