Thread: Reading from file

Hello to all.

I'm a newbie at C programming and this forum as well. A friend told me that I could get some good advice regarding C programming here.

I've written a simple program which ask user to put student name and result. ( the input will be saved into a file called "test.dat")

I'm having a problem with the program I wrote. I was able to compile and run it and it did work. The only problem was it won't display the student name and mark.

here is the code

Code:

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

	struct student
	{
		char name[20];
		int result;
	}	s1[100];


	main()
	{
		int menu,stuNum,counter;
	
	
		printf("1.Add\n\n");
		printf("2.Display\n\n");
		printf("3.Exit\n\n");
		printf("Select Menu: ");

		scanf("%d", &menu);
		
		if(menu == 1)
		{
		 FILE *fp;
		 fp = fopen("test.dat", "w");

			system ("cls"); 
			printf("How many student result do you wish to enter? ");
			scanf("%d", &stuNum);

			for(counter = 0; counter < stuNum; counter++)
			{
				printf("\nEnter student name: ");
				scanf("%s", s1[counter].name);

				printf("Enter student result: ");
				scanf("%d", &s1[counter].result);

			}

		 fclose(fp);
		}


		if (menu == 2)
		{	

			FILE *fp;
			char ch;
			fp = fopen("test.dat","r");
			if (fp == NULL)
			{
				printf("can't open file");
				exit(1);
			}

			ch = getc(fp);
			while(ch!=EOF)
			{
				putchar(ch);
				ch=getc(fp);
			}
			fclose(fp);

			system ("cls"); 
		}

		if (menu == 3)
		{
			system ("cls"); 
			exit(1);
		}
	}

I was hoping you guys can help me to solve this problem. I'll post in the code I've written. I hope someone can give me some insights on how I can solve this...


Thanks in advance.

Code:

			for(counter = 0; counter < stuNum; counter++)
			{
				printf("\nEnter student name: ");
				scanf("%s", s1[counter].name);

				printf("Enter student result: ");
				scanf("%d", &s1[counter].result);
			}

		 fclose(fp);
		}

In the above code you seems to be doing all fine..

which statement of urs puts the data that u enter on the screen , into the file.. ??

:-) happy debugging..

I tried to change this part

Code:

for(counter = 0; counter < stuNum; counter++)
     {
           print("\nEnter student name: ");
           scan("%s", s1[counter].name);

           printf("Enter student result: ");
           scanf("%d", &s1[counter].result);
     } 

      fclose(fp);
    }

Now the code look like this

Code:

for(counter = 0; counter < stuNum; counter++)
     {
           fprintf(fp, "\nEnter student name: ");
           fscanf(fp, "%s", s1[counter].name);

           fprintf(fp, "Enter student result: ");
           fscanf(fp, "%d", &s1[counter].result);
     } 

      fclose(fp);
    }

it gave me error during runtime...
i really don't know where my mistake are.
(i started C 2 weeks ago that is why i don't know how to solve an error)

can u explain where is my mistake ??

hi,


Even this part needs to be taken care of.. U r not reading frm the file..

Code:

while(ch!=EOF)
			{
				putchar(ch);
				ch=getc(fp);
			}
			fclose(fp);

and regarding the err.. what was the err u were getting..

I will just tell to how to go abt but won't take ur pleasure of getting the code rite.. !!! ;-)

happy codeing..

Originally Posted by Micko

I always prefer to clear buffer after input, somewhere this is necessary, and somewhere is not.
Anyway, here's clear_buf function:

Code:

 void clear_buf()
 {
      while(getchar() != '\n');
 }

Won't this cause an infinite loop when getchar() starts returning EOF?

Code:

I always prefer to clear buffer after input, somewhere this is necessary, and somewhere is not.
Anyway, here's clear_buf function:


 void clear_buf()
 {
      while(getchar() != '\n');
 }

thx for the code Miko.

Actually i was hoping that u will explain to me not giving the solution
Thanks again for u'r help

previously the err.. occur in this part

Code:

for(counter = 0; counter < stuNum; counter++)
{
printf("\nEnter student name: ");
scanf("%s", s1[counter].name);

printf("Enter student result: ");
scanf("%d", &s1[counter].result);
}

 fclose(fp);
}

Now everything is fine.
Thanks a lot for your help guys.

Uh but i still don't understand why we use stdout and stdin for file reading

Thank you micko.