need help with a for loop

**tommy69** · 03-10-2004

What I am trying to do is select the number of days that I want to add temperatures. So if I type in 6, then I want to be able to type in 6 temperatures individually, one after the other. However, once I type in the first one and hit enter, the for loops skips through the remaining 5. Once I am able to type in the temperatures for the amount of days I select, I need to calculate the avg temps for those days and display it. Here is my code. Any help would be greatly appreciated. Tommy
[CODE]
#include <stdio.h>
#include <conio.h>

int main()
{

int count, days;
float temp, total, avg;

total=0.0;

printf("\nPlease enter the number of days temperatures you wish to enter: ");
scanf("%d", &days);

for (count=0;count<days;++count)
{
printf("\nTemperature is: ");
scanf("%.2f", &temp);

total=total+temp;

}

avg=total/days;
printf("\n\nThe average temperature was: %5.2f\n", avg);

getch();
return 0;

}

Here is the results so far:

Please enter the number of days temperatures you wish to enter: 6

Temperature is: 54.3

Temperature is:
Temperature is:
Temperature is:
Temperature is:
Temperature is:

The average temperature was: -107374176.00

I now only need to add the temps. Do I need another printf or scanf statement? Thanks again for your help.....

CODE]

**Prelude** · 03-10-2004

>scanf("%.2f", &temp);
Rule 1: scanf is not printf. The two are just similar enough to confuse you. Try this instead:

Code:

scanf("%f", &temp);

**jccharl** · 03-10-2004

change your for statement to read

for(count=0;count<days;count++)
beacuse I think the ++ before count is causing a problem

and when you want to clear the keyboard buffer, if I understand your code correctly, you can write another fuction that uses getchar

i.e

Code:

void clear(){
 while(getchar()!='\n');
}

or you can use fflush and put it after your scanf in your for loop.
Also if you want to add all the temps together you can do that in your for loop for example you could do this after your scanf

temp+=temp

and it should work other than that your code looks great

Hope that helps you and good luck

**tommy69** · 03-11-2004

Thanks for your help. You guys (and gals) really know your stuff. I hope to be just as good some day. After reviewing what you said and applying the different suggestions to my code, the only thing that was wrong with my code was:

Code:

scanf("%.1f", &temp);

....Just take out the .1 and just have %f instead works great.

Can you explain why the the %1.f was causing me the problem? The ++count works fine and I ran the code using ++count and ran it using the count++ and they both ran identically. I was just curious as to why a .1f can make a HUGE impact on my code!! I understand that scanf isnt the same thing as printf and I was using scanf to to accept user input. Anyways, you fixed my dilema. I really appreciate it. Have a great day!! Tom

**tommy69** · 03-11-2004

Thanks for your help. You guys (and gals) really know your stuff. I hope to be just as good some day. After reviewing what you said and applying the different suggestions to my code, the only thing that was wrong with my code was:

Code:

scanf("%.1f", &temp);

....Just take out the .1 and just have %f instead works great. The program adds the temps and creates the averages fine. I didnt need the fflush as well, even though it probably wouldn't hurt :-)

Can you explain why the the %1.f was causing me the problem? The ++count works fine and I ran the code using ++count and ran it using the count++ and they both ran identically. I was just curious as to why a .1f can make a HUGE impact on my code!! I understand that scanf isnt the same thing as printf and I was using scanf to to accept user input. Anyways, you fixed my dilema. I really appreciate it. Have a great day!! Tom

**tommy69** · 03-11-2004

Thanks for your help. You guys (and gals) really know your stuff. I hope to be just as good some day. After reviewing what you said and applying the different suggestions to my code, the only thing that was wrong with my code was:

Code:

scanf("%.1f", &temp);

....Just take out the .1 and just have %f instead works great. The program adds the temps and creates the averages fine. I didnt need the fflush as well, even though it probably wouldn't hurt :-)

Can you explain why the the %1.f was causing me the problem? The ++count works fine and I ran the code using ++count and ran it using the count++ and they both ran identically. I was just curious as to why a .1f can make a HUGE impact on my code!! I understand that scanf isnt the same thing as printf and I was using scanf to to accept user input. Anyways, you fixed my dilema. I really appreciate it. Have a great day!! Tom

**Prelude** · 03-11-2004

>beacuse I think the ++ before count is causing a problem
This possibility only exists when the increment (or decrement) is embedded in a larger expression. Whe used alone, ++i and i++ are equivalent.

Code:

void clear(){
 while(getchar()!='\n');
}

Or more generally:

Code:

void clear ( FILE *in )
{
  int c;

  while ( ( c = fgetc ( in ) ) != EOF && c != '\n' )
    ;
}

Of course, if you find yourself doing this often it's a sign that your input algorithms are possibly flawed.

>or you can use fflush
Or not. Using fflush on input streams is undefined and quite wrong. fflush ( stdin ) is one of the constructs that the majority of this forum's members can spot immediately and give a detailed explanation of why it's wrong.

>Can you explain why the the %1.f was causing me the problem?
The %f flag for scanf doesn't support a precision specification. By trying to use one the flag is malformed and results in undefined behavior, which on your system results in scanf failing with odd results.

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need help with a for loop

Thanks jccharl

Thanks jccharl

Thanks jccharl