I'm too lazy to think of a decent thread title, or to bother formatting the code

[david123]

Well im trying to create a program to do a program for a store, but im stuck when trying to input and read prices from a text file. As you can see from the menu i have alot to do. Any help and advice would be appreciated. I put the main() infront of the change price function to see if it was working.

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<string.h>
/*char menu
{
     int choice
     
     while(choice != 'e') 
     
     printf("Welcome to the REGISTER 2000\n");
     printf("Choose the corresponding letter to choose the option you desire");
     printf("a. Payment\n");
     printf("b. Change price\n");
     printf("c. Veiw stock\n");
     printf("d. Add stock\n");
     printf("e. Exit");
     
     fflush(stdout);
     
     scanf("%c", &choice);
     
     }
     
     
int password
{
char userid[]="zion",password[]="zionatscodz",p[15],u[15];
int n=1,a,b;
printf("Enter USER ID and PASSWORD below (You have only three chances to enter)\n");
getchar();
while(n<=3)
{
 
printf("\nUSER ID: ");
scanf("%s",u);
printf("\nPASSWORD: ");
scanf("%s",p);
a=strcmp(u,userid);
b=strcmp(p,password);
if(a==0&&b==0)
{
printf("You have logged in successfully.\n");
break;
}
else
{
printf("Wrong PASSWORD and/or USER ID. Now you have %d more chances ", 3-n);
  
}
getchar();
n++;
}
if(n==4)
printf("You can't log in.\n");
getchar();
}

*/
 
main()
{
int i;      
int price;
char item[10];

FILE * fp =fopen("price list.txt","a");
if(!fp)
      {
          printf("the file could not be found, create a file\n");
          getchar();
          return 1;
      }
printf("Input prices\n");    
for (i=1;i<=10;i++)
{
fscanf(stdin,"%s%d",item,&price);
fprintf(fp,"%s%d",item,&price);
}
fclose (fp);
fprintf(stdout,"\n\n");
fp=fopen("price list.txt","a");
printf("Item  price");
for(i=1;i<=10;i++)
{
fscanf(fp,"%s%d%",item,&price );

fprintf(stdout,"%s%d\n",item, price);
}
fclose(fp);
system("PAUSE");
}

[Adak]

When you open the file in append mode, you can't then fscanf() something from it - you're already at the end of the file.

fp=fopen("price list.txt","a");
printf("Item  price");
for(i=1;i<=10;i++)
{
fscanf(fp,"%s%d%",item,&price );

fprintf(stdout,"%s%d\n",item, price);
}

[david123]

so i would have to put "r" instead of "a"??

[Adak]

If you want to read data from a file, then yes - open it in read ("r") mode. I prefer the explicit "rt" however, instead of just "r".

"r" will use the text or binary mode that is set by an environmental variable or other config file for your compiler.

somebody else may not have that configuration - I don't, for one.

[david123]

actully sorry i want to write to it, but when i try to it doesnt work

[Dino]

Ah, the "it doesn't work bug". We fixed that last week. Please search the forum.

[dwks]

fscanf(fp,"%s%d%",item,&price );

I think that extra % might be giving you grief.

By the way: fprintf(stdout, ...) is exactly the same as printf(...), and fscanf(stdin, ...) is exactly the same as scanf(...).

FWIW, you're also missing some semicolons and curly braces in some of that commented-out code.

[Adak]

When you open the file in append mode, you can't then fscanf() something from it - you're already at the end of the file.

fp=fopen("price list.txt","a"); 
/* you've opened the price list.txt file, and put the file pointer at the very end of it*/



printf("Item  price");
for(i=1;i<=10;i++)
{

/* now you're trying to read from the price list.txt folder - and you'll find 
nothing, because you're already at the end of the file */
fscanf(fp,"%s%d%",item,&price );


//for the love of Mike - use printf() instead of fprintf(stdout)
fprintf(stdout,"%s%d\n",item, price); 
}

When you get your file mode coordinated with your file operation, your data will be read and written OK.

You're close, David!