Thread: Can't understand what I'm doing wrong.

Write a program which stores coded information about sales for customers. Each customer has a unique number from 1 to 100. The program prompts the user for :

1. the customer number
2. the first letter of the customer's last name
3. the amount of the customer's latest purchase.

It stores the letter in one array and the purchase amount in another. There should be no more than two arrays in your program.

The program will keep asking for this info until the user enters a customer number of zero.


To print the sales amount in dollars and cents, use the $%.2f format specifier.

On screen it should look like this:

customer number? 12

first letter of customer’s last name? J

amount of purchase? 57.62

This is what I have so far:

Code:

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

int main() {

	int num;
	char lastname[1];
	float tempnum;
	float purchase[100];


	do {
		printf("Customer number: \n");
		scanf("%d", &num);
		printf("1st letter: \n"
		getche();
		char lastname[1] = getche;
		printf("Amount of purchase: \n");
		scanf("$%.2f", &tempnum);
		purchase[100] = tempnum;
		} while(num!= '0');

	return 0;

}

I thought I was doing this right, but when I tried to execute this program, it couldn't run beacuse there were errors. If anyone could look over what I have and offer some tips on what I' m doing wrong, I would greatly appreciate it.

Thank You.

And what were the errors?

Helpful hints:

• FAQ > How do I... (Level 1) > Get a line of text from the user/keyboard (C)
• FAQ > How do I... (Level 1) > How do I get a number from the user (C)

Oops!!! I can't belive I didn't see that!!!! I now fixed that & now there's one error left. Thank You for pointing that out.

OK, here's my updated program.

Code:

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

int main() {

	int num;
	char lastname[1];
	float tempnum;
	float purchase[100];


	do {
		printf("Customer number: \n");
		scanf("%d", &num);
		printf("1st letter: \n");
		getche();
		char lastname = getche();
		printf("Amount of purchase: \n");
		scanf("%.2f", &tempnum);
		purchase[100] = tempnum;
		} while(num!= '0');

	return 0;

}

I assume this is what you have now....

Code:

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

int main() {

	int num;
	char lastname[1];
	float tempnum;
	float purchase[100];


	do {
		printf("Customer number: \n");
		scanf("%d", &num);
		printf("1st letter: \n");
		getche();
		lastname[1] = getche();
		printf("Amount of purchase: \n");
		scanf("%f", &tempnum);
		purchase[100] = tempnum;
		} while(num!= '0');

	return 0;

}

The problem is here....

PHP Code:

        printf("1st letter: \n");
        getche();
        lastname[1] = getche();
        printf("Amount of purchase: \n"); 


The getche() function takes one keystroke from the keyboard and echoes the key pressed. In this case first getche(); takes the keystroke W (from your example) and then lastname[1]=getche(); waits for another keystroke. Which I am assuming is when you press the Enter Key, which is another keystroke which is echoed. So it's echoing a carriage return, but not a newline (or is it vice versa? I get confused on the 2 terms sometimes) which basically pushes the cursor back to the beginning of the line but does not step down to a new line. The following printf("Amount of purchase: \n"); then prints from that point. Causing the illusion of printing over the W.


Not only that, but the only thing stored in lastname[1] is the carriage return, not the letter you pressed. And it's beyond me why you're setting up a 1 character array. Just use a char type variable.

A simple solution (other than considering a complete rewrite) would be to lose the first getche() function call, and add a \n to the beginning of the printf's conversion string.

Consider using getchar() vs getche() (since getche isn't portable anyhoo).

Originally Posted by linuxdude

try using a standard function that is implemented almost the same way(except it returns an int) getchar()
so
first change

Code:

char lastname[1] = getche;

to

Code:

lastname[0] = getchar();

and aslo

Code:

char lastname[1];

to

Code:

int lastname[1];

Didn't we just go over this? Must have been someone else...

Unless the value is EOF, it is perfectly fine to assign the return value of getch* to a char. So there is no need to make lastname an int.

Although I do question the logic of using a one element array...

However, what's being forgotten (that you've stated, that they're likely ignoring) is that array indexing starts at zero. So the line should be again, accessing element zero, and not one.

Quzah.