Reading single chars from 'cin' c++

mb1 · #1 31-Mar-2005, 15:12

I've used getline(cin, MyChar) to get the info. Now I need to read each character and then output it. If the character is a number then I output the name of the number. ie "zero" for '0'

swayp · #2 31-Mar-2005, 15:50

Try using cin.get or getch

davekw7x · #3 01-Apr-2005, 09:49

Quote:

Originally Posted by mb1

I've used getline(cin, MyChar) to get the info. Now I need to read each character and then output it. If the character is a number then I output the name of the number. ie "zero" for '0'

If MyChar is an array of char, just use a loop to step through the chars on the line.

THen for each char you could use a switch statement:

CPP / C++ / C Code:

  switch(MyChar[i]) {
    case '0': cout << "zero";
    break;

    case '1': cout << "one";
    break;

...

    case '9': cout << "nine";
    break;

    default: cout MyChar[i];
  }
  cout << " "; //or whatever

Regards,

Dave

mb1 · #4 01-Apr-2005, 11:24

Here's what I have so far. I get an error for my if function. I want to see if I am at the end of my string so I can get a false and terminate the program.

CPP / C++ / C Code:

/*Write a program that copies the characters in standard input stream, cin,
to standard output stream, cout, except for the digit characters.  For a digit 
character, the program displays the digits name. ie: "Zero" for '0'.*/

#include <iostream>
#include <conio.h>
#include <string>
using namespace std;

int main()
{
	//Step01: Declare Memory Locations
	string InputLine;
	string Input;
	//Character position
	
	bool Continue = true;
	//Step02: Initialize Memory Locations
	int Index = 0;
	string MyChar = Input.substr(Index, 1);
	//Step03: Do the Work
	//Step03a: Ask for the characters
	cout << "Enter characters: ";
	cin >> Input;
	//Step03b: Output the characters
	//getline(cin, Input, '\n');
	while(Continue)
	{if(Input = '\n')
	{Continue = false;}
	else if(MyChar == "0")
		{cout << "zero" << endl;
		Index++;}	
	else if(MyChar == "1")
		{cout << "one" << endl;
		Index++;}
	else if(MyChar == "2")
		{cout << "two" << endl;
		Index++;}
	else if(MyChar == "3")
		{cout << "three" << endl;
		Index++;}
	else if(MyChar == "4")
		{cout << "four" << endl;
		Index++;}
	else if(MyChar == "5")
		{cout << "five" << endl;
		Index++;}
	else if(MyChar == "6")
		{cout << "six" << endl;
		Index++;}
	else if(MyChar == "7")
		{cout << "seven" << endl;
		Index++;}
	else if(MyChar == "8")
		{cout << "eight" << endl;
		Index++;}
	else if(MyChar == "9")
		{cout << "nine" << endl;
		Index++;}
	else 
	 	{cout << MyChar << endl;
	 	Index++;}

	}
	//Step04: Wrap and Exit
	cout << endl;
	getch();
	return 0;
}

davekw7x · #5 01-Apr-2005, 12:03

Quote:

Originally Posted by mb1

Here's what I have so far. I get an error for my if function. I want to see if I am at the end of my string so I can get a false and terminate the program.

Input is a string. What are you trying to do with this?

CPP / C++ / C Code:

if(Input = '\n')

This tries to set the string Input to the char '\n' (which is what your compiler is complaining about).

Now, you probably meant to use "==" instead of "=", maybe like this:

CPP / C++ / C Code:

if(Input == '\n')

but it still does not compute. You can't compare a string with a char.

Note that chars in a C++ string can be accessed by using an index, just like an array of char.

That is, the i'th char of the string "Input" is Input[ i ].

Before you try to apply a bandage to this program, I suggest you step back a little and ask yourself the following question:

What do you really want to do?

You must answer that for yourself, but I'm guessing it's probably something like the following. (This is what I am getting from your code; I don't suggest that this is Good or Bad; you define how you want to do it.)

CPP / C++ / C Code:

  continue = TRUE;
  cin.getline(...
  while(continue) {
    //If it is a blank line, set continue to FALSE
   // If it is not a blank line then step through the input string
   // a char at a time.
    // if the char is '0', '1', '2',...'9' print out the string "zero", or "one", or ...
   // if the char is not a digit, print out the char

   // after processing the complete line, then get the next line
    cin.getline(...
  }

So: you have two loops: the outer loop reads lines until the user enters a blank line.

For each no-blank line, an inner loop looks at each char in the line, and print something appropriate.

If this is not what you want to do, then write it down, and tell us.

Then write code that implements the outer loop (reads a line and writes it back out, and stops when the user enters a blank line).

When you have done this, then attack the inner loop: step through the line a char at a time and print something for digits, something else for non-digits.

Etc.

Regards,

Dave

mb1 · #6 01-Apr-2005, 12:11

/*Write a program that copies the characters in standard input stream, cin,
to standard output stream, cout, except for the digit characters. For a digit
character, the program displays the digits name. ie: "Zero" for '0'.*/

You're right. That's what I want to do. I want my if() to ask if there are more characters or not. If no more characters, then terminate the loop.

My error is that I thought

Code:

if(Input = '\n')

asked if the program had another character to check or not.

Thanks for your time.

WaltP · #7 01-Apr-2005, 12:17

You'll get better results if you change MyChar from string to char. That way you only have to deal with one character instead of an entire string containing one char. Your if statements then become

CPP / C++ / C Code:

case '0':

, or use a switch() statement.

Also, to get the benefit of Index you have to create a loop that exits when Index passes the last character of the input string.

You will also benefit from looking over this information on formatting code.

WaltP · #8 01-Apr-2005, 12:22

Ahh, I see you do have a loop which I didn't see because of the formatting. You incremented Index but never retrieved the next character.

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