I am in a programming class since 2 weeks and have some trouble with scanning keyboard input an assigning it to a variable in C.
#include <stdio.h>
#include <stdlib.h>
int main()
{
float creditSum, interestRate, repayment;
system("clear");
printf("\n please enter the total Credit sum: ");
scanf("%.2f", &creditSum);
printf("\n Please enter the interest rate: ");
scanf("%.2f", &interestRate);
printf("\n Please enter the monthly repayment amount: ");
scanf("%.2f", &repayment);
printf("\n\n %.2f | %.2f | %.2f\n\n", creditSum, interestRate, repayment);
return 0;
}
I can compile an run the program but am getting
user@db10:~/$ ./credit
please enter the total Credit sum: 100
Please enter the interest rate:
Please enter the monthly repayment amount:
0.00 | 0.00 | 0.00
So I still can enter the first of 3 values, which is not assigned to the variable as planned.
The course teacher has everybody add a fflush(stdin) before the scanf() on windows machines but this does not work for me (in a linux environment).
I have seen some issues here dealing with the fflush on linux issue, but can't really apply anything successfully for my case (which may be due to me being a complete novice in coding).
Can anyone help here?
The teacher takes a "can't troubleshoot Linux problems as Windows is the OS of choice" approach, so there is not help to be expected from that side.
The scanf catches the input format that is not expected.
The right code should be this:
#include <stdio.h>
#include <stdlib.h>
int main()
{
float creditSum, interestRate, repayment;
system("clear");
printf("\n please enter the total Credit sum: ");
if(scanf("%f", &creditSum)!= 1) return -1;
printf("\n Please enter the interest rate: ");
if(scanf("%f", &interestRate)!= 1) return -1;
printf("\n Please enter the monthly repayment amount: ");
if(scanf("%f", &repayment)!= 1) return -1;
printf("\n\n %.2f | %.2f | %.2f\n\n", creditSum, interestRate, repayment);
return 0;
}
You probably don't want to capture only 2 decimal of the float. You want take the float number and then print it with only 2 decimal.
In any case is important to check the return value of the scanf:
On success, the function returns the number of items of the argument list successfully filled. This count can match the expected number of items or be less (even zero) due to a matching failure, a reading error, or the reach of the end-of-file.
because it can avoid bugs on code.