Code having error with print floating point number & how to sort by element in a struct

Question

I'm a college student learning code C and I have some problem with my C assignment (Managing products). My code below has problem with the output. The prices of products always are bunch of 0.00 no matter what are the input. What's wrong with that?? and BTW, how to apply this How to sort an array of structs in C? into my code?? My program would sort the products by price. Could someone help me plz?? That's would be awesome, sorry if the code is long

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

void input();
void menu();
void read();

struct product
{
  char code[20];
  char name[50];
  int quan;
  float pr;
};

void menu()
{
  int k;
  printf("___________MENU________\n");
  printf(
      "1. Enter the info of your products which is saved in      Products.txt\n");
  printf("2. Read the file Products.txt & sort by price.\n");
  printf("3. Exit");
  printf("________________________\n");
  printf("Enter your option: ");
  fflush(stdin);
  scanf("%d", &k);

  switch (k)
  {
  case 1:
    input();
    break;
  case 2:
    read();
    break;
  case 3:
    printf("\nTerminating");
    exit(0);
    break;
  default:
    printf("\nError! Wrong Number is Entered\nPlease Try Again\n");
    break;
  };
}

void input()
{
  struct product proinfo[50];
  FILE *fp;
  int n, i;

  printf("How many products need imported?\n");
  scanf("%d", &n);

  if ((fp = fopen("Products.txt", "wb")) == NULL )
  {
    printf("Error opening file!\n");
    exit(0);
  }

  for (i = 0; i < n; i++)
  {
    printf("Code of product # %d: ", i + 1);
    fflush(stdin);
    gets(proinfo[i].code);
    printf("Name: ");
    gets(proinfo[i].name);
    printf("Quantity: ");
    scanf("%d", &proinfo[i].quan);
    printf("Price: ");
    scanf("%.2f", &proinfo[i].pr);

  }

  if (fp != NULL )
  {
    for (i = 0; i < n; i++)
      fwrite(&proinfo[i], sizeof(struct product), 1, fp);
    fclose(fp);
  }

}

void read()
{
  struct product a[50];
  int len, t, r;

  FILE *fp;
  fp = fopen("Products.txt", "rb");

  if (fp != NULL )
  {
    fseek(fp, 0, SEEK_END);
    len = ftell(fp);
    t = len / sizeof(struct product);
    rewind(fp);
    fread(&a[0], sizeof(struct product), t, fp);

    for (r = 0; r < t; r++)
    {
      printf("%s \t %s \t %d \t %.2f\n", a[r].code, a[r].name, a[r].quan,
          a[r].pr);
    }
    fclose(fp);
  }
  else
    printf("No data!");
}

int main(void)
{
  int a;
  for (a = 0;; a++)
  {
    menu();
  }
}

Your question is **two** (unrelated) questions. So better split it. — alk, Dec 20 '13 at 10:06
Compile this with all compiler warnings switched on (`-Wall -Wextra -pedantic` for gcc). And then fix the code until no more warnings are issued. — alk, Dec 20 '13 at 10:17
@haccks i'm sorry but what is MS-WIN?? is that a kind of IDE? I code on DevC — D.T, Dec 20 '13 at 11:02
@alk I'm using Dev C and there is no warnings, (will split it, thanks) — D.T, Dec 20 '13 at 11:05

score 2 · Accepted Answer · edited Dec 20 '13 at 10:11

2

You have to use %f instead of %.2f when adding a product:

scanf("%f", &proinfo[i].pr);

edited Dec 20 '13 at 10:11

DontVoteMeDown

21,122
10
69
105

answered Dec 20 '13 at 09:52

Kuro13

105
1
9

2

please explain the reason for that. – 0xF1 Dec 20 '13 at 09:54
The format for `scanf` has a maximum field width, but no precision as `printf` has. The format specifier doesn't allow a dot between the ´%` sign and the conversion specifier. The conversion spec `%.2f` is malformed and the compiler warns about it when warnings are on. – M Oehm Dec 20 '13 at 09:59
%.2f is used to set a display to be x.xx and can't be used to formating user input... – Kuro13 Dec 20 '13 at 10:00

Code having error with print floating point number & how to sort by element in a struct

1 Answers1