Need help with a C program exercise

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So I'm currently writing a program that sort of functions like an order invoice. The user inputs the price of the items and the number of items he wants.

Example
1.42 - Price
2.25
30.21
0 200 -Item Number and Quatity
1 400
2 100

So my problem is how do I differentiate between the Price inputs and Item Number, Quantity input?

What I have tried:

I have written

Objective-C

#include <stdio.h>

int main(void)
{
	
	int item ;
	float value;
	float price[300];
	for (item = 0;( Missing Condition to exit);item++)
	{
		scanf("%f",&value);	
		price[item]=value;
		      
			
	
	}	
	
	
}

Which works for inputting the item price.
I do not know how to transition to Item Number and Quantity inputs.

Posted 27-Oct-17 4:31am

Crulas

Updated 27-Oct-17 5:38am

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Comments

Rick York 27-Oct-17 11:35am

It appears to me the differences are a price has a decimal point in the string and an item number has a space in the string. That would be one place to start.

Rick York 27-Oct-17 13:25pm

Try this :

gets( buffer ); // obtain a string from the user
if( strchr( buffer, ' ' ) )
{
// space detected - read item and quantity
}
else
{
// no space - must be a price
}

2 solutions

Solution 2

Think about how you would do this in a shop.

You: I would like to buy some widgets.
Shopkeeper: Certainly madam, which size?
You: the big ones.
Shopkeeper: And how many would you like?
... etc.

So you need to do something similar.

Print a message asking for some information.
Read the user's response.
Check that what they have entered is valid.
Repeat the above for each item of information.
Do the various calculations.
Print the results.

Posted 27-Oct-17 5:38am

Richard MacCutchan

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CPallini · Accepted Answer · 2017-10-27T05:35:00

Assuming your input is without remarks, i.e.

You could read the whole line, the test if it contains two integers (no. and quantity) or just a float (price). That is

C

#include <stdio.h>

#define ITEMS 300
int main(void)
{
  float price[ITEMS];
  int items = 0;

  int item_no;
  int item_qty;

  char line[80];

  while ( fgets(line, sizeof(line), stdin) && items < ITEMS )
  {
    if ( sscanf(line, "%d %d", &item_no, &item_qty) == 2)
    {
      if  (item_no < items)
        printf("item n. %d, item quatity %d, price = %f\n", item_no, item_qty, price[item_no] * item_qty);
    }
    else
    {
      if ( sscanf(line, "%f", &price[items]) == 1)
        ++items;
    }
  }
  return 0;
}