output is displayed zero...no errors..

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C++

/*to evaluate exponent*/
#include<stdio.h>
#include<conio.h>
int main()
{
    clrscr();
    int i,exp;
    float tot=1,num;
    printf("enter the number and the exponent to which it should be raised:");
    scanf("%f,%f",&num,&exp);
    for(i=1;i<=exp;i++){
        tot=tot*num;
    }
    printf("the required value of the exponent is  %f",tot);
    getch();
    return 0;
}

[Edit: Fixed code formatting, added indention, added some line feeds]

Posted 20-Dec-14 3:24am

Member 11324568

Updated 20-Dec-14 3:56am

Jochen Arndt

v2

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Jochen Arndt · Accepted Answer · 2014-12-20T03:53:00

Solution 1

The second argument to your scanf function is of type int but you use the float "%f" format specifier.

You must use the "%d" int format specifier:

scanf("%f,%d",&num,&exp);

Posted 20-Dec-14 3:53am

Jochen Arndt

Comments

CPallini 20-Dec-14 10:01am

5.

Member 11324568 20-Dec-14 10:07am

that doesnt work...first i did the above thing ,..second time to use decimals in the entered nuumber i changed the code.both arent working

Jochen Arndt 20-Dec-14 10:17am

It is working for me. I have just compiled and tested it.

You may insert this line after the scanf call to see what is not working:
printf("\nYou entered: %f,%d\n",num, exp);

Or use the debugger as suggested by Griff.

Member 11324568 20-Dec-14 11:04am

:)

OriginalGriff · Accepted Answer · 2014-12-20T03:58:00

Solution 2

Come on now!
This is your second question today, and they are both fairly simple things that a quick check with a debugger would have found.

SO, lets try and debug it shall we?
Use the debugger: put a breakpoint on the line:

C++

scanf("%f,%f",&num,&exp);

And run your program.
When it stops, single step the debugger and enter your two numbers: "2,3" will do.
When you press ENTER, you will be back to the debugger.
So - look at the two numbers you just entered.
What's the value of num? For me, it's 2.0000000
What's the value of exp? For me it's 1077936128

Now, that's not right!
So look at your code, and see if you can see why it's wildly inaccurate!
What is the difference between the two variables num and exp and how you use them?

Posted 20-Dec-14 3:58am

OriginalGriff

Comments

CPallini 20-Dec-14 10:01am

5.

Member 11324568 20-Dec-14 10:10am

sorry,here i have given the wrong thing...i have done it using the correct ones..i.e i used int-%d and float -%f ..yet it doesn work..please check it..the entered values are correct but the value shows zero sometimes else it shows 1

OriginalGriff 20-Dec-14 10:26am

And what happens when you use the debugger?
Because when I fix the format / variable type problem, "2,3" gives me "8.0000000" which is what I expect.

Please, try the debugger - it lets you see exactly what you code is doing - input, output, and what path the code is taking. It's a skill - and you don't develop it by getting others to fix problems! :laugh:
I'll help you look at it, but you so need to do most of the work. ;)

So make a note of your input, check the values in the num and exp variables are correct, and follow the code through. At what point does it get the wrong value, and where?

Member 11324568 20-Dec-14 10:37am

ok thanks griff...and today is my second day of programming and i'm trying to learn myself...so you cant expect me to be an expert..atleast i tried to complete loops in few hours,..thanks for helping...and btw i don't even know what a debugger is..i have been just into converting all the maths functions i knew into c language...blindly...

Member 11324568 20-Dec-14 10:30am

@originalgriff please reply! does changing the format working form your compiler?for me its showing value as 1 now..

OriginalGriff 20-Dec-14 10:34am

Yes: if I change exp to a float, or change the format string to "%f,%d". Both ways I get "2,3" giving "8.0000000" which is what I expect.

So what do you get in num and exp?

Member 11324568 20-Dec-14 10:41am

i will send you a screenshot.. :( why is it working for all and not for me?

Member 11324568 20-Dec-14 10:38am

i changed both to %d i get 2,3 and result is 1...i am not understanding what the mistake is!

OriginalGriff 20-Dec-14 10:46am

"btw i don't even know what a debugger is"

OK - that we have to fix! :laugh:
A debugger is a way to run your program so that you can stop it when you want, and look at what variables are doing.
So what are you using to compile and run this? Hopefully, it's Visual Studio (and if it isn't, then is there a reason why you are using what you are?)

OriginalGriff 20-Dec-14 10:47am

And BTW: Is there a good reason why you are starting with C?
C# is a lot easier to get the hang of in many ways...

Member 11324568 20-Dec-14 10:53am

yes because after winter vacation..we have c language in our semester...and i am enrolled in computer science..so i have started to learn it before hand...i use turboc 4+..and i dont know what to use..i have downloaded this not knowing other compilers :( ..
and why am i getting output as 1 though the input is given as 2 3

OriginalGriff 20-Dec-14 11:00am

Um...isn't that 20 years old?
Does it still run on modern computers? :laugh:

OK - do you have any idea what your course is going to use? Because there is a good chance it won't be that old...

Get a copy of Visual Studio (Express for C++ should do fine, and it's free from Microsoft) and I'll show you how to get it working with "just C" rather than C++.
(if you get VS2010 Express it'll be easier - I use 2010 Professional as I'm skipping at least one version this time)
You can download it here:
http://www.visualstudio.com/en-us/downloads#d-2010-express

Member 11324568 20-Dec-14 11:24am

thanks a lot griff :) ..well our course consists of c..i'll download this visual studio.....thanks again...

OriginalGriff 20-Dec-14 11:27am

Trust me on this: it's the best development environment known to developers. Bar none. When you have to work in anything else after VS, you will hate it!

And the Express versions are free - and cover 90% of what the paid versions do :OMG:

Member 11324568 20-Dec-14 11:37am

:) Yes it is better than turbo c++ which hangs every now and then..

PIEBALDconsult 20-Dec-14 11:55am

Bushwah! Turbo C is da bomb!

OriginalGriff 20-Dec-14 12:02pm

It was damn good in it's time, yes...but we though that about Mullets, and flairs, and the Bay City Rollers...

OK, scratch the last one. *Nobody* over the age of ten thought they were any good. :laugh:

debashishPaul · Accepted Answer · 2014-12-20T04:01:00

Solution 3

Because exp is an int but you read it as a float

Change

C++

scanf("%f,%f",&num,&exp);

to

C++

scanf("%f,%d",&num,&exp);

Posted 20-Dec-14 4:01am

debashishPaul

Comments

Member 11324568 20-Dec-14 10:15am

that didn't work debashish...in my turboc i have done it correctly...here i typed it wrong...i used int-%d float-%f yet its showing 0 or 1 AS output