DaniWeb Forum Index > Software Development > C++

C++ RSS

C4552: '>' : operator has no effect

Thread Solved

•

Join Date: May 2008

Posts: 96

Reputation: QuantNeeds is an unknown quantity at this point

Solved Threads: 0

QuantNeeds QuantNeeds is offline

Offline

Junior Poster in Training

C4552: '>' : operator has no effect

Jun 16th, 2008

Help – for both of my for header components, error reads the following, but I do not understand how to fix this because I am not sure what is wrong about it. Please help.

warning C4552: '>' : operator has no effect; expected operator with side-effect

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 
void inputGrades (int numStudents,int numGrades)
{
	for(numStudents > 0; numStudents -= 1;)
	{
		cout << "For this student enter the grades.";
		double score = 0;
		double grade, avg;
 
		int exams = numGrades;
		for(exams > 0; exams -= 1;)
		{
			cout << "Grade: ";
			cin >> grade;
			score += grade;
		}
 
		avg = static_cast<double>(score) / numGrades;
		cout << "The average test score for the student is: " << avg << endl;
	}
}
 
int main()
 {
	 int students, tests;
 
	 cout << "Enter the number of students: ";
	 cin >> students;
	 cout << "Enter the number of tests: ";
	 cin >> tests;
 
	inputGrades(students, tests);
 
 cout << endl;
 return 0;
 
 } // end main
void inputGrades (int numStudents,int numGrades)
{
	for(numStudents > 0; numStudents -= 1;)
	{
		cout << "For this student enter the grades.";
		double score = 0;
		double grade, avg;

		int exams = numGrades;
		for(exams > 0; exams -= 1;)
		{
			cout << "Grade: ";
			cin >> grade;
			score += grade;
		}
		
		avg = static_cast<double>(score) / numGrades;
		cout << "The average test score for the student is: " << avg << endl;
	}
}

int main()
 {
	 int students, tests;

	 cout << "Enter the number of students: ";
	 cin >> students;
	 cout << "Enter the number of tests: ";
	 cin >> tests;

	inputGrades(students, tests);

 cout << endl;
 return 0;

 } // end main

•

Join Date: Jun 2008

Posts: 973

Reputation: Alex Edwards is a jewel in the rough

Solved Threads: 107

Alex Edwards Alex Edwards is offline

Offline

Posting Shark

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

Odd, I'm not getting that error at all...

Did you include the preprocessor directives for cstdlib and iostream? Also are you using namespace std?

It ran fine for me, no weird operator errors.

•

Join Date: Jun 2008

Posts: 9

Reputation: TacklesMcCaw is an unknown quantity at this point

Solved Threads: 2

TacklesMcCaw TacklesMcCaw is offline

Offline

Newbie Poster

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

•

Originally Posted by QuantNeeds

Help with Code Tags

C++ Syntax (Toggle Plain Text)
 
	for(numStudents > 0; numStudents -= 1;)
for(numStudents > 0; numStudents -= 1;)

Generally it's good form to declare the variables used in the for loop, like:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
for (numStudents; numStudents > 0; numStudents--)
for (numStudents; numStudents > 0; numStudents--)

I don't know if the compiler considers what you've done an error, but it might, I've never actually tried it anyway besides the three section for declaration above. That might be your problem. Also, is your compiler just spitting out a warning or an error, they're different.

•

Join Date: Apr 2008

Posts: 296

Reputation: tesuji is on a distinguished road

Solved Threads: 42

tesuji

Offline

Posting Whiz in Training

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

Hi QuantNeeds

•

Originally Posted by QuantNeeds

. . .
warning C4552: '>' : operator has no effect; expected operator with side-effect
. . .
Help with Code Tags

C++ Syntax (Toggle Plain Text)
        int numStudents = 10;  // assignment necessary 
	for(numStudents > 0; numStudents -= 1;)
int numStudents = 10; // assignment necessary for(numStudents > 0; numStudents -= 1;)

Your for loop is correct. It corresponds completely with the Standard ISO/IEC 14882:1998(E) of C++. So your compiler seems to be something outdated, especially the phrase "expected operator with side-effect", what means that an for-init statement would have been expected, tells that your compiler isn't that conform to the standard.

brs,
tesu

•

Join Date: Oct 2006

Posts: 2,752

Reputation: niek_e has a reputation beyond repute

Solved Threads: 294

niek_e

Offline

Posting Maven

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

•

Originally Posted by tesuji

Hi QuantNeeds

Your for loop is correct.

No it's not, TacklesMcCaw is right. There's a semicolon in the wrong place:
this: for(numStudents > 0; numStudents -= 1;)
Should be this: for(;numStudents > 0; numStudents -= 1)

same goes for for(exams > 0; exams -= 1;) ; this should be for(;exams > 0; exams -= 1)

•

Originally Posted by tesuji

So your compiler seems to be something outdated, especially the phrase "expected operator with side-effect", what means that an for-init statement would have been expected, tells that your compiler isn't that conform to the standard.

VS2008 pro will give you the exact same warning-message and I wouldn't call that compiler 'outdated'. The code will compile, but a warning is given to indicate that although the code is 'correct' the user probably made an error.

Last edited by niek_e; Jun 16th, 2008 at 6:50 am.

•

Join Date: Apr 2008

Posts: 296

Reputation: tesuji is on a distinguished road

Solved Threads: 42

tesuji

Offline

Posting Whiz in Training

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

Hi niek_e

You are right, I have overlooked the semicolon at he far right.

Intuitively I also would put a semicolon at left side if for-init statement is off. But the ISO standard tells the opposite. You may have a look at this standard on http://www-d0.fnal.gov/~dladams/cxx_standard.pdf
In the lower half page 95 you will find the definition of the for-loop. Where
you can see that the first semicolon is integral part of the for-init statement,
just consider the gap between for-init statement and condition statement, also see
the given note. That means, if one omits the for-init statement the semicolon also
disappears.

Obviously, almost all C++ compilers do not implement the for loop in concordance with the ISO Standard, do they?

krs,
tesu

•

Join Date: Oct 2006

Posts: 2,752

Reputation: niek_e has a reputation beyond repute

Solved Threads: 294

niek_e

Offline

Posting Maven

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

•

Originally Posted by tesuji

In the lower half page 95 you will find the definition of the for-loop. Where
you can see that the first semicolon is integral part of the for-init statement,
just consider the gap between for-init statement and condition statement, also see
the given note. That means, if one omits the for-init statement the semicolon also
disappears.

I've read it and it appears you're right, but I've never seen a compiler that will compile this:

 Help with Code Tags 
 cpp Syntax (Toggle Plain Text) 
int a = 0;
for (a<50;a++)
int a = 0;
for (a<50;a++)

•

Originally Posted by tesuji

Obviously, almost all C++ compilers do not implement the for loop in concordance with the ISO Standard, do they?

Apparently not

Last edited by niek_e; Jun 16th, 2008 at 9:11 am.

•

Join Date: Aug 2005

Posts: 15,142

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1434

Ancient Dragon Ancient Dragon is offline

Offline

Most Valuable Poster

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

The for statement is actually explained on page 97. paragraph 6.5.3.3 shows the correct syntax. Without doing any research I'll bet there has been a later correction to 6.5.3.1 and what was shown at the botton of page 95.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: May 2008

Posts: 351

Reputation: Radical Edward has a spectacular aura about

Solved Threads: 62

Radical Edward Radical Edward is offline

Offline

Posting Whiz

Re: C4552: '>' : operator has no effect

Jun 16th, 2008

> That means, if one omits the for-init statement the semicolon also disappears.
That's not quite right, but Edward can easily see why you'd think that. Like most stuff in the standard, you have to look in several different places to get the whole picture. Specifically, the syntax for a for loop is:

Help with Code Tags

(Toggle Plain Text)

for ( for-init-statement condition(opt) ; expression(opt) ) statement

The first semicolon is missing because it's implied to always exist. You can see that if you follow the production for for-init-statement:

Help with Code Tags

(Toggle Plain Text)

for-init-statement:
        expression-statement
        simple-declaration

In 6.2 on page 93 you find the production for expression-statement and 7 on page 101 is the production for simple-declaration:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
expression-statement:
        expression(opt) ;
 
simple-declaration:
        decl-specifier-seq(opt) init-declarator-list(opt) ;
expression-statement:
        expression(opt) ;

simple-declaration:
        decl-specifier-seq(opt) init-declarator-list(opt) ;

The semicolon isn't optional in expression-statement or simple-declaration, and for-init-statement isn't optional either. This means that a semicolon is always required, even if the for-init-statement is otherwise empty.

> Obviously, almost all C++ compilers do not implement the for loop in concordance with the ISO Standard, do they?
It's not obvious to be sure, but almost all compilers seem to get it right.

Keep reading the standard! It's good to challenge assumptions with your own interpretation and we can all learn from this kind of discussion.

Last edited by Radical Edward; Jun 16th, 2008 at 10:24 am.

If at first you don't succeed, keep on sucking until you do succeed.

•

Join Date: May 2008

Posts: 96

Reputation: QuantNeeds is an unknown quantity at this point

Solved Threads: 0

QuantNeeds QuantNeeds is offline

Offline

Junior Poster in Training

Re: C4552: '>' : operator has no effect

#10

Jun 16th, 2008

This was the quickest solution that helped. This is what I changed it to:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 
	for(numStudents; numStudents > 0; numStudents -= 1)
	{
		double score = 0;
		double grade, avg;
 
		for(int exams = numGrades; exams > 0; exams -= 1)
		{
			cout << "Grade: ";
			cin >> grade;
			score += grade;
		}
	for(numStudents; numStudents > 0; numStudents -= 1)
	{
		double score = 0;
		double grade, avg;
		
		for(int exams = numGrades; exams > 0; exams -= 1)
		{
			cout << "Grade: ";
			cin >> grade;
			score += grade;
		}

•

Originally Posted by TacklesMcCaw

Generally it's good form to declare the variables used in the for loop, like:
Help with Code Tags

C++ Syntax (Toggle Plain Text)
for (numStudents; numStudents > 0; numStudents--)
for (numStudents; numStudents > 0; numStudents--)
I don't know if the compiler considers what you've done an error, but it might, I've never actually tried it anyway besides the three section for declaration above. That might be your problem. Also, is your compiler just spitting out a warning or an error, they're different.