Programming Forums > Application Development > C++

andrewgray · Jul 2nd, 2005, 3:29 PM

I bought the C++ Weekend Crash Course, and when I came across this problem I checked online and apparently this program is in several books.

Note, this is the SAMPLE compile out of the book. It's supposed to work as a demo to learn how to compile a program.

Here's the program as it appears in the book:

(Toggle Plain Text)

#include <iostream.h>
#include <stdio.h>

int main (int nNumberofArgs, char* pszArgs[]) {

	int nCelsius;
	cout << "Enter the temperature in Celsius:";
	cin > nCelsius;
	
	int nFactor;
	nFactor = 212 - 32;
	
	int nFahrenheit;
	nFahrenheit = nFactor * nCelsius/100 + 32;
	
	cout << "Fahrenheit value is:";
	cout << nFahrenheit;

    return 0;
}

Problem: upon compile in both Visual C++ 6.0 (Windows) and XCode (Macintosh) (I haven't tried it on my Linux compy yet), the compiler has a problem with the line that reads

(Toggle Plain Text)

cin > nCelsius;

in the program. Microsoft Visual C++ 6.0 and XCode alike give me the error message "error: no match for 'std::istream& > int&' operator".

It's exactly what the book says! What am I doing wrong?

EverLearning · Jul 2nd, 2005, 3:31 PM

I think it was a typo.
Try

(Toggle Plain Text)

cin >> nCelsius;

i.e. double ">"

Mjordan2nd · Jul 2nd, 2005, 5:44 PM

Yup. That should do the trick by the looks of it. Good luck! Let us know if you have any other problems.

DaWei · Jul 2nd, 2005, 6:41 PM

You may need to specify the namespace, either by adding:

(Toggle Plain Text)

using namespace std;

below the includes OR by using

(Toggle Plain Text)

std::cout << whatever;
std::cin >> whatever;

grumpy · Jul 2nd, 2005, 10:13 PM

.... and using <iostream> and (optionally) <cstdio> rather than <iostream.h> and <stdio.h> respectively.

<stdio.h> is supported from C++, because of backward compatibility to C. <iostream.h> has never been standard C++; any book that uses it probably dates from days when the C++ standard was an evolving draft. <iostream.h> was quickly superseded by <iostream>.

chanti · Jul 5th, 2005, 9:45 AM

It could be syntax error
Give
cin >> nCelsius;

chanti · Jul 5th, 2005, 9:49 AM

Hi dawai;

I have one doubt. 'cin', 'cout' are c++ key words. why we need name spaces.
I think this platform dependent.
I have tried in Turbo c++, I didn't get any errors.
Can please give me detailed description?
regards
chakri

Ooble · Jul 5th, 2005, 10:19 AM

cin and cout are NOT C++ keywords. They're functions, defined in the iostream header file. You need to tell the compiler you're using the std namespace because that's where they are - in the std namespace.

If you're using iostream.h, stop now. That header file was created before the C++ standard was finalised - it's obsolete now. Use iostream instead, as grumpy suggests, and either prefix all the standard functions with "std::" (this includes things from fstream, etc.), or type using namespace std; after you include your header files.

DaWei · Jul 5th, 2005, 11:01 AM

Actually, cin and cout are not functions. The are stream objects. The functions are in the insertion and extraction operators << and >>. Those operator functions return (in the absence of error) a reference to the stream, which is why they may be chained together. Since the objects are defined in the std namespace you must either use that namespace or qualify them at the time of use. It seems like a pain in the butt at times, but there's nothing to preclude you from defining your own object and naming it "cin".

Ooble · Jul 5th, 2005, 2:14 PM

Whoops... knew I got something wrong. Well, ya learn something new every day, don't ya?

Jul 2nd, 2005, 3:29 PM	#1
andrewgray Newbie Join Date: Jul 2005 Location: Seattle, WA Posts: 3 Rep Power: 0	Fahrenheit / Celsius compile problem I bought the C++ Weekend Crash Course, and when I came across this problem I checked online and apparently this program is in several books. Note, this is the SAMPLE compile out of the book. It's supposed to work as a demo to learn how to compile a program. Here's the program as it appears in the book: (Toggle Plain Text) #include <iostream.h> #include <stdio.h> int main (int nNumberofArgs, char* pszArgs[]) { int nCelsius; cout << "Enter the temperature in Celsius:"; cin > nCelsius; int nFactor; nFactor = 212 - 32; int nFahrenheit; nFahrenheit = nFactor * nCelsius/100 + 32; cout << "Fahrenheit value is:"; cout << nFahrenheit; return 0; } #include <iostream.h> #include <stdio.h> int main (int nNumberofArgs, char* pszArgs[]) { int nCelsius; cout << "Enter the temperature in Celsius:"; cin > nCelsius; int nFactor; nFactor = 212 - 32; int nFahrenheit; nFahrenheit = nFactor * nCelsius/100 + 32; cout << "Fahrenheit value is:"; cout << nFahrenheit; return 0; } Problem: upon compile in both Visual C++ 6.0 (Windows) and XCode (Macintosh) (I haven't tried it on my Linux compy yet), the compiler has a problem with the line that reads (Toggle Plain Text) cin > nCelsius; cin > nCelsius; in the program. Microsoft Visual C++ 6.0 and XCode alike give me the error message "error: no match for 'std::istream& > int&' operator". It's exactly what the book says! What am I doing wrong?

Jul 2nd, 2005, 3:31 PM	#2
EverLearning Hobbyist Programmer Join Date: May 2005 Location: Indiana Posts: 130 Rep Power: 4	I think it was a typo. Try (Toggle Plain Text) cin >> nCelsius; cin >> nCelsius; i.e. double ">" __________________ got math? yumm... "All men by nature desire to know" -Aristotle, Metaphysics

Jul 2nd, 2005, 5:44 PM	#3
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	Yup. That should do the trick by the looks of it. Good luck! Let us know if you have any other problems. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Jul 2nd, 2005, 6:41 PM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	You may need to specify the namespace, either by adding: (Toggle Plain Text) using namespace std; using namespace std; below the includes OR by using (Toggle Plain Text) std::cout << whatever; std::cin >> whatever; std::cout << whatever; std::cin >> whatever; __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jul 5th, 2005, 10:19 AM	#8
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	cin and cout are NOT C++ keywords. They're functions, defined in the iostream header file. You need to tell the compiler you're using the std namespace because that's where they are - in the std namespace. If you're using iostream.h, stop now. That header file was created before the C++ standard was finalised - it's obsolete now. Use iostream instead, as grumpy suggests, and either prefix all the standard functions with "std::" (this includes things from fstream, etc.), or type using namespace std; after you include your header files. __________________ Me :: You :: Them

Jul 2nd, 2005, 10:13 PM	#5
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,223 Rep Power: 5	.... and using <iostream> and (optionally) <cstdio> rather than <iostream.h> and <stdio.h> respectively. <stdio.h> is supported from C++, because of backward compatibility to C. <iostream.h> has never been standard C++; any book that uses it probably dates from days when the C++ standard was an evolving draft. <iostream.h> was quickly superseded by <iostream>.

Jul 5th, 2005, 9:45 AM	#6
chanti Newbie Join Date: Jul 2005 Location: HYDERABAD(INDIA) Posts: 4 Rep Power: 0	It could be syntax error Give cin >> nCelsius;

Jul 5th, 2005, 9:49 AM	#7
chanti Newbie Join Date: Jul 2005 Location: HYDERABAD(INDIA) Posts: 4 Rep Power: 0	Hi dawai; I have one doubt. 'cin', 'cout' are c++ key words. why we need name spaces. I think this platform dependent. I have tried in Turbo c++, I didn't get any errors. Can please give me detailed description? regards chakri

Jul 5th, 2005, 11:01 AM	#9
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Actually, cin and cout are not functions. The are stream objects. The functions are in the insertion and extraction operators << and >>. Those operator functions return (in the absence of error) a reference to the stream, which is why they may be chained together. Since the objects are defined in the std namespace you must either use that namespace or qualify them at the time of use. It seems like a pain in the butt at times, but there's nothing to preclude you from defining your own object and naming it "cin". __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jul 5th, 2005, 2:14 PM	#10
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Whoops... knew I got something wrong. Well, ya learn something new every day, don't ya? __________________ Me :: You :: Them

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Programming Forums > Application Development > C++

Fahrenheit / Celsius compile problem