Thread: help with struct, c-programming

I use Microsoft visual studios 2012 and i don't know what im doing wrong, can someone correct me?

i get the debug Assertion failed

line 55

Expression: (str!=NULL)

I pointed out where line 55 is to make it easier.

Code:

#include<stdlib.h>
#include<stdio.h>
#define size 1


struct students
{
    char last[15], first [15];
    int t1,t2,t3;
    float avg;
    char grade;
};
void load (struct students s[], int n)
{
int i;
for (i=0; i<n; i++)
{ 
printf("Enter last name");
gets(s[i].last); 
printf("Enter first name");
gets(s[i].first);
printf("Enter three scores");
scanf("%d%d%d",&s[i].t1,&s[i].t2, &s[i].t3);
s[i].avg=(s[i].t1+s[i].t2+s[i].t3)/(float)3;
if(s[i].avg>70)
    s[i].grade ='P';
    else
s[i].grade ='F';
fflush(stdin);
}
}
void print(struct students s[],int n)
{
int i;
for (i=0; i<n; i++)
{
printf("%s%s\n",s[i].first, s[i].last);
printf("test scores: %d %d %d \n",s[i].t1, s[i].t2, s[i].t3);
printf("average grade: %f %%\n\n",s[i].avg, s[i].grade);
}
}
void sort(struct students s[], int n)
{
int i,j;
students t;
for(i=0;i<n-1;i++)
for(j=0;j<n-1;j++)
if (s[i].avg<s[j+1].avg)
{
t=s[i];
s[i]=s[j+1];
s[j+1]=t;
}
}
void pass(struct students s[], int n)               //Source.cpp<-- line 55
{
int count=0, i;
for(i=0; i<n; i++)
    if (s[i].grade = 'P')
    count ++;
    printf("number of passes %d\n\n",count);
}
void savetext(struct students s[], int n)
{
int i;
FILE *f;                //file pointer
f=fopen("C:\\ student.txt","w");        //("C:\\student.txt")<- C will greate the file if dont exist but C will not create the folder
for (i=0; i<n; i++)
{
    fprintf(f,"%s\n",s[i].last);
    fprintf(f,"%s\n",s[i].first);
    fprintf(f,"%d%d%d%f%c\n",s[i].t1, s[i].t2,s[i].t3,s[i].avg,s[i].grade);
}
fclose(f);
}
void gettext(struct students s[], int n) //<---- struct (name)
{
    int i;
    FILE *f;  
    f= fopen("c:\\students.txt","r"); //<---- \\ name
    for(i=0; i<n; i++)
    {
        fgets(s[i].last,sizeof(s[i].last),f);
        fgets(s[i].first,sizeof(s[i].first),f);  // \n acts like an fflush
        fscanf(f,"%d%d%d%f%c\n", &s[i].t1, &s[i].t2,&s[i].t3, &s[i].avg,&s[i].grade);
    }
fclose(f);
}
void savebin(struct students s[],int n)
{
    FILE *f;
    f=fopen("c:\\students.bin","wb");


    fwrite(&s,sizeof(s[0]),n,f);  //&s is a reference to the array to save sizeof(s[0]) size of each array element
            //n is how many array elements are there
            //f is file pointer
fclose(f);
}


void getbin(struct students s[],int n)
{
FILE *f;
f=fopen("c:\\students.bin","rb");
fread(&s,sizeof(s[0]),n,f);
fclose(f);
}


void main()
{
students s[size];
load(s,size);
sort(s,size);
print(s,size);
pass(s,size);
savetext(s,size);
gettext(s,size);
print(s,size);
savebin(s,size);
getbin(s,size);
print(s,size);
system("pause");
}

In addition to the comments by whiteflag,

Code:

f=fopen("C:\\ student.txt","w");

looks a bit weird

thank you for pointing out the errors. this was suppose to be an example from my professor and i had a hard time running it cuz he hand writes his codes and he has a messy handwriting.

Originally Posted by jcun3

thank you for pointing out the errors. this was suppose to be an example from my professor and i had a hard time running it cuz he hand writes his codes and he has a messy handwriting.

Just a quick hint: When in the context of programming, the plural of code is code. "codes" is a pet hate of mine.

Your professor might be interested in any of the numerous technologies that will project a computer screen. If he used one, he wouldn't have to hand write the code anymore; not to mention, it would probably be better since he would be encouraged to write it and compile it from an editor.

the file specific is f:\dd\vctools\crt_bld\self_x86\crt\src\fprintf.c

Well, this is why I told you to check for a valid file handle.
Don't assume everything will go well.
If you do something like

Code:

FILE *f = fopen("C:\\sstudents.txt", "r");

The example file sstudents.txt probably doesn't exist, (it's actually a spelling problem) so f becomes NULL.