hi all,
Im planning to use FILE to set up a student database.May i know how do i create the text file(Eg:student.txt)?
It seems that i just have to type all the info in a text editor and save as .txt file.How must I arrange the info and link it to my program?
I've read notes and also searched the website, but all i get is teaching me how to read and write from a file but not creating that .txt file.
Thanx for ya time!
If you open a file for writing and it gets created. Look up fopen in your man/help pages.I've read notes and also searched the website, but all i get is teaching me how to read and write from a file but not creating that .txt file.
7. It is easier to write an incorrect program than understand a correct one.
40. There are two ways to write error-free programs; only the third one works.*
I have 1 small program which has all file operation,However I've used binary mode for files.
Use binary mode files instead of .txt.Binary files are far more better than ordinary text file.
File modes
rb = binary read
wb = binary write
ab = append binary
heres my code compiled with gcc 3.4 on linux but functions are same across windows & linux
Code:#include <stdio.h> struct rec { int roll,t; }; int main() { struct rec r; FILE *fp; int i,j; fp=fopen("abc.dat","wb+"); /* open file in read & write mode u can use ab+ also */ if(fp==NULL) { printf("\nError opening file"); return -1; } /* this part writes in file */ for(i=0;i<5;i++) { r.roll = i + 1; r.t = 0; fwrite(&r,sizeof(r),1,fp); /* write to file */ } /* till here */ rewind(fp); while(1) { if(feof(fp)) break; fread(&r,sizeof(r),1,fp); if(r.roll == 2) { printf("\nStudent with rollno %d found",r.roll); break; } } /* This part reads from file & prints*/ rewind(fp); for(i=0;i<5;i++) { fread(&r,sizeof(r),1,fp); /* read from file */ printf("\nRoll = %d , t = %d",r.roll,r.t); } /* till here */ fclose(fp); /* close file */ }
Last edited by vinit; 04-12-2006 at 03:05 AM.
Hi vinit...thanks for da reply!
For my student database which consist :
Student name,ID,Year of degree,Major,Courses name and id,total credit hours,Grades for each course,GPA,Dean's list.
Is is okay if i use text file(.txt)?Coz im a newbie and im not really sure how to use binary files.
Actually my question is :How do i put all those student info above into my database?
Do i have to input it through my program by using the fwrite function?Or i just create a .txt file and type all the info in it, then i can just open it with my program to read later?
sorry to make u confused with my questions, hope someone can understand me here....
sherwi, please go through code that I've posted.
Try to understand it.Its very basic code,learn it u'll get ur answers by yourself.
No Thats not the way to create file,create file using fopen(),get all data from set of scanf statement in structure & then write it to file using fwrite().Go through the code its very basic & u must read file I/O in C before coding,if you are not able to understand it then its really difficult for everyone to help u here.Do i have to input it through my program by using the fwrite function?Or i just create a .txt file and type all the info in it, then i can just open it with my program to read later?
Last edited by vinit; 04-12-2006 at 05:17 AM.
ok, i'll try then..thanx for the codes !
If it okay if i don't use scanf statements to get all the data?Instead i just initialize all the data in structure and write it to a file.Will it work the same?
Also, how can i open that binary file that i've created to view?I wont see anything if i open a binary file using a text editor right?
It is ok if u initialise all parameters & then write to file,but then for that u've to create that much large array.Instead u can us 1 variable of ur structure & 1 loop to put many records in files.So its on u which way u like.
To view binary files U'll need hex editor which are freely available on net.
You can write anything to a file: random strings, user input, hardcoded values. If you work with binary files, use fread() and fwrite(); if you want to read from plain text files use fprintf(), fscanf() and fgets(). Reading from plain text is arguably easier, but more space might be required, and you will need to do some basic error handling. Doing it in binary gives you full control, but don't expect to be able to edit your records reasonably easily in Notepad.
If you open a binary file in Notepad, it depends on what you've stored. It could simply be jumbled-looking English; or you could be staring at a whole lot of plain rubbish, especially if you write raw struct data or something, using, say, pointers.
Code:#include <stdio.h> void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){ puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9 /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i] ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][ t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}
Erm...i don't quite understand what u mean by this.Mind to explain?thanxInstead u can us 1 variable of ur structure & 1 loop to put many records in files
And in English please --Instead u can us 1 variable of ur structure & 1 loop to put many records in files
Erm...i don't quite understand what u mean by this.Mind to explain?thanx
This is what i've come up with.Is this the right way?But when i run it, it looks abit weird, i dunno if it's correct.Code:#include <stdio.h> struct A{ char name[50]; char id[8]; char year[8]; char grade[3]; }; struct Record{ char name[30]; long int id; char year[8]; char major[20]; struct A course[6]; int credit_hours; float gpa; char deanlist[4]; }; int main() { struct Record student[13]; FILE *infile; int i,j; for(i=0;i<13;i++){ printf(“Please enter student info\n”); scanf(“%s %ld %s %s %d %f %s”,student[i].name,&student[i].id,student[i].year,student[i].major,&student[i].credit_hours,&student[i].gpa,student[i].deanlist); for(j=0;j<6;j++){ printf("Please enter course info\n"); scanf("%s%s%s%s",student[i].course[j].name,student[i].course[j].id,student[i].course[j].year,student[i].course[j].grade); } } if((infile=fopen("student.txt","w"))==NULL) printf("Error\n"); else{ for(i=0;i<13;i++){ fprintf(infile,"%s%ld%s%s%d%.2f%s",student[i].name,student[i].id,student[i].year,student[i].major,student[i].credit_hours,student[i].gpa,student[i].deanlist); for(j=o;j<6;j++){ fprintf(infile,"%s%s%s%s",student[i].course[j].name,student[i].course[j].id,student[i].course[j].year,student[i].course[j].grade); } } fclose(infile); } return 0; }
Btw, i used text files here.Coz i dunno how binary files can be used with search later in my search and sort program.
Note:The second for loop is to include the data for struct A course.
Since you are using scanf you are going to have to deal with the newline character left over between each scanf call.
Probably better to use fgets and parse the line with sscanf.
You should also check the return codes of your input functions.
Would be much more usable if you prompted for each part individually.
When you write to the file you need to at least separate each piece of data by a space so you can read it back in.Code:for(j=o;j<6;j++){
Newlines for each record as well.
Formatting like this may be more readable
Code:scanf("%s %s %s %s" ,student[i].course[j].name ,student[i].course[j].id ,student[i].course[j].year ,student[i].course[j].grade);
Last edited by spydoor; 04-13-2006 at 09:48 AM.
Thanks spydoor..
Okay, i've changed to fgets to get a string of name for both loops.I think it works for the first loop, but not for the second loop.I can only enter 3 data instead of 4 data.Also, how to parse with sscanf?Code:#include <stdio.h> struct A{ char name[50]; char id[8]; char year[8]; char grade[3]; }; struct Record{ char name[30]; long int id; char year[8]; char major[20]; struct A course[6]; int credit_hours; float gpa; char deanlist[4]; }; int main() { struct Record student[13]; FILE *infile; int i,j; for(i=0;i<13;i++){ printf("Please enter student info\n"); fgets(student[i].name,30,stdin); scanf("%ld %s %s %d %f %s",&student[i].id ,student[i].year ,student[i].major ,&student[i].credit_hours ,&student[i].gpa ,student[i].deanlist); for(j=0;j<6;j++){ printf("Please enter course info\n"); fgets(student[i].course[j].name,50,stdin); scanf("%s %s %s",student[i].course[j].id ,student[i].course[j].year ,student[i].course[j].grade); } } if((infile=fopen("student.txt","w"))==NULL) printf("Error\n"); else{ for(i=0;i<13;i++){ fprintf(infile,"%s %ld %s %s %d %.2f %s",student[i].name ,student[i].id ,student[i].year ,student[i].major ,student[i].credit_hours ,student[i].gpa ,student[i].deanlist); for(j=0;j<6;j++){ fprintf(infile,"%s %s %s %s",student[i].course[j].name ,student[i].course[j].id ,student[i].course[j].year ,student[i].course[j].grade); } } fclose(infile); } return 0; }
One more question, for the second loop(course info), not every student will be taking 6 courses.They can be taking less than that,maybe 3 or 4 courses only.How can i stop the loop when i've entered enough amount of courses taken by the student?
Thanks alot for checking my codes here, u guys help me lots!
Can anyone help me ?plssss....thank you so much
ssharish2005Code:for(j=0;j<6 & ch=='Y';j++) { printf("Please enter course info\n"); fgets(student[i].course[j].name,50,stdin); fgets(student[i].course[j].id,8,stdin); fgets(student[i].course[j].year,8,stdin); fgets(student[i].course[j].grade,3,stdin); clear_buffer(); printf("Want to enter Course ( Y / N)\n"); ch = getchar(); } --------- > clear_bufer fucntion < --------- void clear_buffer(void) // function to cleae the input buffer. NOTE: read FAQ { int ch; while((ch=getchar())!='\n' && ch!=EOF); }
