Posts by LordoftheFly

Anyone know that c program got wat type of error?

Perhaps you're inquiring about a runtime error?

When I think about programming, the two types of errors that I consider to be significant. These are syntactical errors and logical errors.

Syntax concerns the format of your code and whether the computer can understand what your code says.

Logic concerns whether your program does what you intended it to do.

In order to compile, your code requires correct syntax. Logic, however, it does not.

You are losing the precision in your division. You need to cast:

div = (float)num1 / (float)num2;

Your printf requires "%%" to represent a literal % symbol:

printf("> %d %% %d = %d.\n", num1, num2, mod);

Awesome, it worked! Thanks for the coding help. These kinds of details can be tough to iron out sometimes, so I appreciate your assistance.

Honestly, the best place to get your questions answered would be forums like this (or cprogramming.com) where there are people knowledgeable about C.

Much appreciated. This website's forums seem to have the most polite and knowledgable users. I appreciate that response times are generally fast and that answers are decipherable.

Thanks for the info and insights.
- LordoftheFly

Hey guys. Thanks for taking the time to read this post.

I'm relatively comfortable with C++ and am taking a class in C for the first time. I'm finding it difficult and frustrating to adapt to the new language. It's kind of like trying to box with a hand tied behind my back.

At any rate, I have a few general questions and a few specific questions that might help me to better understand general and specific aspects of the language . Feel free to tackle the questions that you'd like.

Is C a subset of C++? Do they share libraries? Are there libraries that are specific to C or C++?

Part of the reason I'm having trouble with C is that I'm finding it difficult to search for answers online. With C++ I can just include the phrase "C++" on any question and I'll arrive at a destination.

With C, however, I'm really not sure what combination of words to add to my search. "C programming," "C language," "C," Any advice?

Additionally, are there any websites that you can point me to for general information on C?

http://www.cprogramming.com/ seems to have some of the information that I'm looking for.

Also, I'm having trouble with a specific piece of code.
This is a homework assignment to explain the relationships between two numbers through addition, subtraction, multiplication, division, and % (modulus?). I'm not sure if it matters, but I work …

http://www.cppreference.com/wiki/io/clear
This site deserves to be on your list of favorites, if it isn't already.

It definitely is now.

Make a function like this (with iostream included and the std namespace):

ostream & Flush (ostream & myStream)
{
myStream.clear();
myStream.ignore(myStream.rdbuf()->in_avail());
return myStream;
}

Then call it for whatever stream you want to clear, and it supports chaining. ie Flush(cin) >> iInput;

I actually had a lot of trouble trying to figure out how exactly to implement the code, and it took three webpages and this thread for the information to make a modicum of sense to me. I came up with this seemingly simple function:

void clear (ios::iostate flags = ios::goodbit);

which I call using the following segment of code, which is partially borrowed from Salem's code:

if ( cin.fail() )
{
  cout << "Failed." << endl;
  cout << "Please do not use the arrow keys." << endl;
  cin.clear();
}

The sources that proved helpful to me are listed here:
http://www.cppreference.com/wiki/io/clear
http://www.cplusplus.com/reference/iostream/ios_base/iostate.html
http://www.cplusplus.com/reference/iostream/ios/clear.html

It seems that this problem is solved, so thank you to everyone who contributed time and information to my code.
-- LordoftheFly

while ( cin.getline(input1, 31, '\n') ) {
  cout << "--" << input1 << "--" << endl;
}
if ( cin.fail() ) {
  cout << "Failed" << endl;
}
if ( cin.eof() ) {
  cout << "EOF" << endl;
}
if ( cin.bad() ) {
  cout << "bad, very bad" << endl;
}

This is a clever test. Thanks for this insight.

If you use an arrow key, what happens here?
- loops a few times, then prints one of the exit messages?
- loops a few times, printing various fragments of the edited input, then goes back to waiting.

When I use the arrow keys it prints "Failed." And according to the link "Once set, the fail state will make all other operations on the stream fail instantly, until the error state is cleared with the clear function." (http://www.cppreference.com/wiki/io/fail)

So it sounds like the fail flag is being tripped, would which apparently cause my program to go haywire. I'm looking around and can't seem to find any information on the "clear function."

Oh, and please find a way of copying the code accurately (pen drive, email yourself, whatever). It'll save a lot of confusion in the long run.

I shall try. Again, thanks for your patience and input.

> strcyp (input1, default1);
Does this compile?
Isn't it supposed to be strcpy() ?

Sorry about this one. I had to retype the code on another computer to put it online; so no.. it probably wouldn't compile. Additionally, on line 14, a correction would have to be made to cause the program to go into that while loop.

It would be changed from:

while ((success != 0) && (tries < 4))

to

while ((success == 0) && (tries < 4))

> the program will ignore (or seem to ignore) all of my "cin.ignore(1000, '\n');" and
> "cin.getline(input1, 31, '\n');" commands.
Or they could be returning error.
Check the return result to see if this is the case.

I checked the value of input1 by adding the following code after the if-statement that starts on line 30.

cout << "input1 =" << input1 << "!" << endl;

I experimented with different input and arrow key combinations, and came to some realizations.

1. I started with the standard input that I used for all of the debugging:
Guybrush Threepwood T2345
2. When I used any left-right combination that started with the left arrow, the output always came out the same (regardless of whether or not I replaced characters.):

input1 =Guybrush Threepwood T234ome text here...
Some more text here...

3. When I used any left-right combination that started with the right arrow, I got:

input1 =Guybrush Threepwood T2345 ome …

I'm having trouble with this section my code and am hoping that you can help me diagnose and solve the problem. I'm not sure if it makes a difference, but I compile and run my code in Cygwin.

The problem:
At run time when the program asks for the user input I can input somethimg like: "Guybrush Threepwood Throe" and the code will run just fine, but if I type the same thing and then use the left arrow button to move the cursor back over the input to make a correction (for instance to change the third word of the input from "Throe" to "Three"), the program will ignore (or seem to ignore) all of my "cin.ignore(1000, '\n');" and "cin.getline(input1, 31, '\n');" commands. I'm aware that you're not technically supposed to use the arrow keys in Cygwin, but I'm trying to make my code fool-proof.

Why does this happen, and assuming the user will eventually use those arrow keys, how can I prevent the undesired side-effects?

#include <cstdlib>
#include <iostream>
using namespace std;

int main ()
{
  char input1[31];
  char default1[31] = "                              ";
  int success = 0;
  int tries = 0;
  while ((success != 0) && (tries < 4))
  {
     cout << "[By what name shall you be known? Max: 30 Characters]" <<   endl;
     cout << ":" << endl;
  // Point of possible conflict follows immediately
     cin.getline(input1, 31, '\n');
     if (((input1[0] > 64) && (input1[0] < 91)) || ((input1[0] > 96) && (input1[0] < …