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C programming. my printf("%i",  total);

Posted on 2008-10-09
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Last Modified: 2012-05-05
when i key in the values

4 2.5
5 9.6
3 8.6
3 1.6
1 7.6
2 9.5
5 0.6
2 4.9

the program gives me  127 instead of 128
what should i add to the code to solve the bug.
#include <stdio.h>
//file used to log the data is named "log.out"//
#define LOG "log.out"
#include <math.h>
 
int main(void)
{
 
//declare variables//
int new_customer, qty;
double amt, total =0;
FILE *log;
 
//open file with write function//
log = fopen(LOG, "w");
 
//start the loop//
printf("New Customer? (1 for yes; 0 for no): ");
scanf("%i",&new_customer);
printf("\n");
 
while(new_customer)
{
//reset total amount to zero//
total = 0.00;
 
//ask cashier to enter quantity and amount//
printf("Enter quantity and amount (-1 -1 to quit): ");
//program assign the values entered to the identifiers//
scanf("%i %lf",&qty, &amt);
 
while (qty > 0)
{
//prints data entered to "log.out"//
fprintf(log, "%i %.2f ", qty, amt);
//calculates the total result in floating point//
total += qty * amt;
//ask cashier to enter quantity and amount//
printf("Enter quantity and amount (-1 -1 to quit): ");
scanf("%i %lf", &qty, &amt);
}
//adds sentinal points to the file "log.out"//
fprintf(log,"-1 -1"); 
//show the cashier the amount to collect from the customer.//
total = (ceil(total * 100))/100;
printf("The total purchase is : $%i", (int)total);
//prints the total amount collected, actual amount and the amount of losses//
//to the file "log.out"//
fprintf(log, "\n%i %.2f %.2f\n\n",(int)total, total, total - (int)total);
 
printf("\n\nNew Customer? (1 for yes; 0 for no): ");
scanf("%i",&new_customer);
printf("\n");
 
} 
system("PAUSE");	
//quits the program//
return 0;
}

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Question by:Zhongcai
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9 Comments
 
LVL 45

Expert Comment

by:sunnycoder
ID: 22678593
Works for me

]$ ./a.out
New Customer? (1 for yes; 0 for no): 1

Enter quantity and amount (-1 -1 to quit): 4 2.5
Enter quantity and amount (-1 -1 to quit): 5 9.6
Enter quantity and amount (-1 -1 to quit): 3 8.6
Enter quantity and amount (-1 -1 to quit): 3 1.6
Enter quantity and amount (-1 -1 to quit): 1 7.6
Enter quantity and amount (-1 -1 to quit): 2 9.5
Enter quantity and amount (-1 -1 to quit): 5 0.6
Enter quantity and amount (-1 -1 to quit): 2 4.9
Enter quantity and amount (-1 -1 to quit): -1 -1
The total purchase is : $128

New Customer? (1 for yes; 0 for no): 0

What platform are you executing on?
0
 
LVL 45

Expert Comment

by:Kent Olsen
ID: 22678651
Hi Zhonqcai,

I run the program with the same data and get 128.

What compiler/system are you using?


Kent
0
 
LVL 1

Accepted Solution

by:
rgoble earned 50 total points
ID: 22678659
If you are wanting it to round the value of total up before printing it out there is an easier way to do it. Change the line

total = (ceil(total * 100))/100;

to

total = Math.Round( (total+0.5), 0);

The round function rounds to the nearest value, since you are wanting to round up you need to first add 0.5.
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LVL 45

Expert Comment

by:Kent Olsen
ID: 22678673
Oop.

Sorry Sunny.  I was testing the code and didn't see your post.....


Kent
0
 
LVL 45

Expert Comment

by:sunnycoder
ID: 22678879
No issues :)

0
 

Author Comment

by:Zhongcai
ID: 22678905
thanks guys. I pasted my friend's solution to the question. I was wondering if there is anything better than

total = (ceil(total * 100))/100;

and i guess

total = Math.Round( (total+0.5), 0);

works better
0
 
LVL 45

Expert Comment

by:sunnycoder
ID: 22679029
Does Math.Round(a,b) work with a C compiler?
0
 
LVL 53

Expert Comment

by:Infinity08
ID: 22679124
>> total = Math.Round( (total+0.5), 0);

Math.Round is not part of C. It isn't even possible, since C doesn't have the concept of methods.

If you are really working in C, then the accepted solution is not correct.


Try this way of rounding instead :

        int dtotal = ((int) ceil(total * 100.0)) / 100;
        printf("The total purchase is : $%d\n", dtotal);


or more likely, if the total needs to include the cents (up to 2 digits), then :

        total = ceil(total * 100.0) / 100.0;
        printf("The total purchase is : $%.2f\n", total);
0
 
LVL 1

Expert Comment

by:rgoble
ID: 22679401
Math.Round works in C#, or managed c++. I misread the question and though he was using C#.
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