C Replacing Variable Number

Question

Is it possible to automate this program more in order to change the variable number?

    for (i = 1; i < 4; i++)
    {
    printf("Enter the Code for Item #%d: ",i);
    scanf("%d", &CodeNumber1);
    printf("Enter the Price for Item #%d: ",i);
    scanf("%f", &Price1);
    printf("Enter the Quantity for Item #%d: ", i);
    scanf("%d", &Quantity1);
    }

So where the variable has 1 written, would it be possible to replace it with i?

Without using an array

Take a look at this: https://stackoverflow.com/questions/10468128/how-do-you-make-an-array-of-structs-in-c — Fabio_MO, May 02 '18 at 13:02
I'd say no. What are you trying to achieve. This might be an [XY Problem](http://xyproblem.info). What's wrong with using an array? You definitely need one here. — Jabberwocky, May 02 '18 at 13:02
Normally the 1 should be replaced by `[i]` or similar, but for some secret reason you don't want to use arrays. — Gerhardh, May 02 '18 at 13:04
I wanted to see if it'd be possible doing it without an array, thanks though guys, il use an array — VallyMan, May 02 '18 at 13:06
when calling any of the `scanf()` family of functions: 1) always check the returned value (not the parameter values) to assure the operation was successful. — user3629249, May 04 '18 at 09:46

score 3 · Answer 1 · answered May 02 '18 at 13:06

You could use arrays instead of a fix name. For example you could use something like

int CodeNumber[4] = {0};
for (i = 0; i < 4; i++)
{
    printf("Enter the Code for Item #%d: ",i);
    scanf("%d", &CodeNumber[i]);
}

In my opinion an even better approach would be to use structs that hold your 3 integers inside:

struct item {
  int CodeNumber;
  int ...
}

And then use it like this:

struct item myItem[4];
for (i = 0; i < 4; i++)
{
    printf("Enter the Code for Item #%d: ",i);
    scanf("%d", &(myItem[i].CodeNumber));
    ...
}

Quentin · Accepted Answer · 2018-05-02T13:36:06.140

3

Without an array? Challenge accepted. Good thing Boost.Preprocessor also works with C!

#include <boost/preprocessor/repetition/repeat_from_to.hpp>
#include <boost/preprocessor/cat.hpp>

#define LOOP_BODY(z, n, data) \
    printf("Enter the Code for Item #%d: ", n); \
    scanf("%d", &BOOST_PP_CAT(CodeNumber, n)); \
    printf("Enter the Price for Item #%d: ", n); \
    scanf("%f", &BOOST_PP_CAT(Price, n)); \
    printf("Enter the Quantity for Item #%d: ", n); \
    scanf("%d", &BOOST_PP_CAT(Quantity, n));

BOOST_PP_REPEAT_FROM_TO(1, 4, LOOP_BODY, ~)

I am not to be held responsible for any loss of personal or professional reputation, pride, life, limb; or the happenstance of any kind of apocalypse resulting from the use of the code above.

edited May 02 '18 at 13:36

answered May 02 '18 at 13:08

Quentin

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I am not responsible for any loss of SO reputation either :) – Magix May 02 '18 at 13:08
@Quentin OK, I ignored that. Thanks. – Jabberwocky May 02 '18 at 13:09
2

This is the only answer that directly achieves what the OP wanted! :) – Mike Andrews May 02 '18 at 13:10
Nice. Although you might want to mention that the boost preprocessor is guaranteed to work in C. – Bathsheba May 02 '18 at 13:15
@Bathsheba well, I'm not sure why people believe otherwise. The first line of the documentation is *"The Boost Preprocessing library is a library of macros, with support for preprocessor metaprogramming. The library supports both C++ and C compilation."* – Quentin May 02 '18 at 13:16
@Quentin: Well, when old cats like me see a `hpp`, we think C++ header. Just sayin'. – Bathsheba May 02 '18 at 13:17
3

@Bathsheba added note for old cats. – Quentin May 02 '18 at 13:18
@Quentin: Thank you - I've upvoted and am now waiting to pounce on the downvoter. – Bathsheba May 02 '18 at 13:20
Thank you! This is amazing haha – VallyMan May 02 '18 at 14:50

score 0 · Answer 3 · answered May 02 '18 at 13:07

0

You should use an array to hold your variables, like so :

int data[4] = {0};
for(unsigned int i = 0; i < 4; i++) {
    printf("Enter the data for item #%d: ",i);
    scanf("%d", &data[i]);
}

answered May 02 '18 at 13:07

Magix

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C Replacing Variable Number

3 Answers3