Software Testing a C program (Can't see anything wrong)

[Travercraig]

Right this topic i'm doing is about software testing. So I have this specification which reads:

 

1. Average Calculation Program

   This program inputs three (int) values and then asks the user to enter the arithmetic mean (a float value). Then the program calculates the actual mean and checks to see if the user got the answer correct.

   Link to the source code is here: mean.c

   Study the program's specification and source code. Then write down your list of test cases before you compile and run the program. Now test your program against your test cases and record the results. Do you find any errors in the code? If so, make corrections, and then re-try all the test cases. (This is important in case your changes have broken something that used to work.)

    

   So I have the source code here:

   #include <stdio.h>int main(){    int v1, v2, v3;    float user_mean, actual_mean;    printf("Enter 1st value : ");    scanf(" %i", &v1);    printf("Enter 2nd value : ");    scanf(" %i", &v2);    printf("Enter 3rd value : ");    scanf(" %i", &v3);    printf("What is the mean? ");    scanf(" %f", &user_mean);    if (user_mean == (actual_mean = (v1 + v2 + v3) / 3.0))        printf("Correct.  Well done!\n");	    else        printf("Sorry, should be %f\n", actual_mean);        return 0;}//If user enters three values = What is the mean? message (PASS)//If user_mean is correct = Correct well done! message (PASS)//If user_mean is incorrect = Sorry, should be N value message (PASS)//If user_mean = !%f = Error message (FAIL)

   I can't really find that much wrong with it at all. You can see my tests at the bottom in comments.

    

   The only thing i can possibly see wrong is that the user_mean allows for intgers to be entered. but i'm not sure really.

    

   Here is the output of the program for both a correct and incorrect answer:

    

   Can anyone see anything wrong with the program? I mean it's really simple, but this is all about testing software.

    

    

 

[silentmelodies]

Why...do you learn C? School?

[mikat]

 

<snip>

 

 

dont use floats but ints?

[Travercraig]

dont use floats but ints?

Well if you read the requirements "enter the arithmetic mean (a float value)" I don't think I should change it to integers really. This is about reading a spec and testing to make sure you can meet that spec. The program is really simple I know. But it's about testing a spec.

[Travercraig]

Why...do you learn C? School?

Why is that a problem? From what I understand a lot of languages are based off C. So if you know C you know a lot of other languages already. Such as Java, C#, C++ the list goes on.

[NeatSquidYT]

Why is that a problem? From what I understand a lot of languages are based off C. So if you know C you know a lot of other languages already. Such as Java, C#, C++ the list goes on.

C is rarely used by itself nowadays. A lot of languages are based off it, but C code =/= Java code. The only language where C is automatically correct code is C++

[as96]

I'm not sure, what's the issue? What are you trying to do and what's going wrong?

From the picture you posted it looks like you got it working already.

[Stefan1024]

Take care about rounding of floats.

Never do:

Float == float

Use:

Abs(float - float) < 10^(-5)

To compare if they are equal

[Nineshadow]

And what's wrong?

Ah , you need to find mistakes.

[Brenz]

What you have written in the comments of the code are not tests. They are what you think will happen.

 

You actually need to write some test cases and assert that the program produces the expected result.

[LukeTim]

C is rarely used by itself nowadays. A lot of languages are based off it, but C code =/= Java code. The only language where C is automatically correct code is C++

Well that's not true at all.

[as96]

C is rarely used by itself nowadays. A lot of languages are based off it, but C code =/= Java code. The only language where C is automatically correct code is C++

C is still widely used.

[mikat]

C is rarely used by itself nowadays. A lot of languages are based off it, but C code =/= Java code. The only language where C is automatically correct code is C++

in things like arduino it's still used

[silentmelodies]

Why is that a problem? From what I understand a lot of languages are based off C. So if you know C you know a lot of other languages already. Such as Java, C#, C++ the list goes on.

No you...you don't.

Basically with the standard C library you can't write anything. To write a simple GUI program with C it takes a extremely long time and a lot of code. C is old.

Try Python first, or Ruby. There is a reason other languages exist, if C was so superior for everything every program would be written in C.

[silentmelodies]

Well that's not true at all.

 

 

C is still widely used.

C is widely used. 

C is rarely written.

[Nineshadow]

No you...you don't.

Basically with the standard C library you can't write anything. To write a simple GUI program with C it takes a extremely long time and a lot of code. C is old.

Try Python first, or Ruby. There is a reason other languages exist, if C was so superior for everything every program would be written in C.

C is great for beginners to learn programming as a whole. Minus the Object Oriented paradigm.

[silentmelodies]

C is great for beginners to learn programming as a whole. Minus the Object Oriented paradigm.

To learn programming, yes. To build advanced applications, uhm sorry, no.

 

[Nineshadow]

To learn programming, yes. To build advanced applications, uhm sorry, no.

 

Actually...operating systems are built mainly on C, and I wouldn't say those aren't advanced pieces of programming. Still , they would have probably used something else if they had a better choice.

[as96]

Try Python first, or Ruby. There is a reason other languages exist, if C was so superior for everything every program would be written in C.

There is no perfect language, every language has its pros and cons.

[silentmelodies]

Actually...operating systems are built mainly on C, and I wouldn't say those aren't advanced pieces of programming. Still , they would have probably used something else if they had a better choice.

I know. Linux is 100% C. But there is my point, Linux took 10 years to develop to become useable and modern enough to support exotic hardware. So took Windows.

C is wasting time imo

[Stefan1024]

I know. Linux is 100% C. But there is my point, Linux took 10 years to develop to become useable and modern enough to support exotic hardware. So took Windows.

C is wasting time imo

It depends on the platform.

C is ligthweigth and ideal for embedded systems and microcontrollers. For a full sized PC you can afford using a comftabe language that needs more resoucese.

[silentmelodies]

It depends on the platform.

C is ligthweigth and ideal for embedded systems and microcontrollers. For a full sized PC you can afford using a comftabe language that needs more resoucese.

That is my point. Having so powerful PC's, it does not make sense to waste time on C. C is okay for 8MB Flash on a Router, not for a PC.

C++, Java, Python, Ruby etc. are all far superior to C, and they are written, in C.

The mentality: "If i know C i know all the languages." is wrong.

Go write a simple CLI program that displays help when --help is passed and version when --version is passed, and add error handling.

How much time do you need with Python? 

How much time do you need with C?

My time > PC time

If it takes me 2 hours to speed up a program 2 seconds, it is NOT worth it.

[Alim]

Check how it behaves if ends up being decimical fraction. In some cases user won't be able to type exact mean number, and you program will fail

[Nineshadow]

-

It may not be worth it to you , but it will be to other people.

Efficiency is key in a lot of applications.

That's why we have broken games nowadays. Because game devs are kinda ignoring it , being pressured into making games faster and faster by the publishers. Just a very simple example which is felt by pretty much all of us these days.

[Stuff_]

Could we quit arguing availability and usage and actually help OP? 

 

Obviously this is for a class at university. It's beyond his control as to which language he learns inside of his class. If you guys knew as much about languages as you like to assert, then maybe you could help OP?

 

 

 

Comparing for equality with float values could possibly not always give you the correct result (comparison that will be true).

You could compare using epsilon, and you also need to determine how close/precise you would like the results to be.