I want to generate different named function useful for writing unit test cases. I want to do this basically to give unique name to each unit test case.
I am using google test framework for writing unit test cases.
I have to use TEST_Macro to write unit test cases. I want to automatically give incrementing numbers to every unit test.
Here is my (non-working) code:
#include <iostream>
using namespace std;
#define join(x, y) x## y
void join(test, __COUNTER__)()
{
cout << "\n 1";
}
void join(test, __COUNTER__)()
{
cout << "\n 2";
}
int main()
{
cout << "Hello world!" << endl;
test0() ;
test1() ;
return 0;
}
What is the correct way to generate unique function names using __COUNTER__?
So this is the old "paste happens before evaluation of macro arguments", so you get test__COUNTER__ instead of test0.
You need to do a nested macro:
#define expandedjoin(x,y) x##y
#define join(x, y) expandedjoin(x, y)
(The rest of your code gives lots of errors because you are passing a void function to cout, which isn't good)
Complete working code:
#include <iostream>
using namespace std;
#define expandedjoin(x,y) x##y
#define join(x, y) expandedjoin(x, y)
void join(test, __COUNTER__)()
{
cout << "\n 1";
}
void join(test, __COUNTER__)()
{
cout << "\n 2";
}
int main()
{
cout << "Hello world!" << endl;
test0();
test1();
return 0;
}
Related
New to C++
My understanding is endl will add a new line. So with the following piece of code:
#include <iostream>
using namespace std;
void printf(string message);
int main()
{
cout << "Hello" << endl;
cout << "World" << endl;
printf("Hello");
printf("World");
return 0;
}
void printf(string message) {
cout << message << endl;
}
I expect the output to be:
Hello
World
Hello
World
But, strangely, the output is:
Hello
World
HelloWorld
Looks like, when called from the user-defined method, endl is not adding new line..??
What is wrong with my understanding here. Please advise.
The problem is that due to overload resolution the built in printf function is selected over your custom defined printf function. This is because the string literal "Hello" and "World" decays to const char* due to type decay and the built in printf function is a better match than your custom defined printf.
To solve this, replace the printf calls with :
printf(std::string("Hello"));
printf(std::string("World"));
In the above statements, we're explicitly using std::string's constructor to create std::string objects from the string literal "Hello" and "World" and then passing those std::string objects by value to your printf function.
Another alternative is to put your custom printf inside a custom namespace. Or you can name your function other than printf itself.
It's using the inbuilt printf method.
Try to explicitly use std::string so that it'll call custom printf method.
printf(std::string("Hello"));
printf(std::string("World"));
Or you can put your method in a different namespace:
#include <iostream>
namespace test
{
extern void printf(const std::string& message);
}
int main()
{
std::cout << "Hello" << std::endl;
std::cout << "World" << std::endl;
test::printf("Hello");
test::printf("World");
return 0;
}
void test::printf(const std::string& message) {
std::cout << message << std::endl;
}
try renaming the "printf" function to "print" it works fine-
#include <iostream>
using namespace std;
void print(string message);
int main()
{
cout << "Hello" << endl;
cout << "World" << endl;
print("Hello");
print("World");
cout <<endl;
return 0;
}
void print(std::string message) {
cout << message << endl;
}
You should pick function name other than printf(); like Print().
This question already has answers here:
When to use extern in C++
(4 answers)
Closed 3 years ago.
I've got aud.ccp, aud.h, geist.ccp, geist.h. In geist.ccp I've got a variable which needs to get to aud.ccp.
If I got:
int x = 5;
in geist.ccp, how can I achieve it, that a 8 gets represented in the console when I use
cout << x+y << endl;
as well as
cin >> y; // ofc I enter 3 here.
in aud.ccp.
Edit:
I wrote:
int x
in the public part of geist.h
and I wrote:
x = 5;
in geist.cpp.
Finaly I wrote
extern int x;
in aud.cpp
But somehow I do not get the result I want
You need to declare the variable in a public scope of one module:
int x;
and declare its use in another one:
extern int x;
Then both modules, when linked together, will use the same variable.
It's most conveniently done with the defining declaration (with an optional initializer) placed in a .cpp module, and the extern declaration put into a .h file. Then each module, both the one defining the variable and those importing it, see the same extern declaration, which guarantees the declaration is same as an actual definition of the variable.
You have to care about "redefinition x variable Error" in your code.
You can Try this method:
geist.h:
#ifndef GEIST_H
#define GEIST_H
int x {5};
#endif
geist.cpp:
#include "geist.h"
#include <iostream>
using namespace std;
void printname()
{
cout << "The X value is" << x <<"\n";
}
aud.h:
#ifndef AUD_H
#define AUD_H
extern int x;
void Add_X_with_User_Desire();
#endif
aud.cpp:
#include "aud.h"
#include <iostream>
using namespace std;
void Add_X_with_User_Desire()
{
int y{0};
cout << "Please Enter an Integer Number: "<< "\n";
cin >> y;
cout << "y + x: " << x+y<<"\n";
}
and finally main function:
stack59228825.cpp:
#include <iostream>
#include "aud.h"
int main()
{
std::cout <<"X variable in main function is:" <<x << "\n";
Add_X_with_User_Desire();
x = 10;
std::cout << "targetVariable in main function is:" << 10 << "\n";
Add_X_with_User_Desire();
}
I have 2 .cpp files called "FactoringProgram.cpp" and "FactoringProgram2nd.cpp", also 1 header file called "FactoringProgram.h". I've already tried searching for this problem on StackOverflow and a couple other sites and haven't found a solution that worked for me. When I try to run this command: "g++ FactoringProgram.cpp FactoringProgram2nd.cpp" I get this error:
FactoringProgram.cpp: In function ‘int main()’: FactoringProgram.cpp:8:11: error: request for member ‘InitialMessage’
in ‘Problem1’, which is of non-class type ‘Factoring()’
Problem1.InitialMessage();
The code for "FactoringProgram.h" is:
#ifndef FactoringProgram_h
#define FactoringProgram_h
#include <stdio.h>
#include <iostream>
class Factoring
{
private:
int m_FirstCoefficent;
char m_FirstOperator;
int m_SecondCoefficent;
char m_SecondOperator;
int m_3rdExpression;
public:
Factoring();
int InitialMessage();
};
#endif
FactoringProgram.cpp code:
#include <stdio.h>
#include <iostream>
#include "FactoringProgramH.h"
int main()
{
Factoring Problem1();
Problem1.InitialMessage();
return 0;
}
FactoringProgram2nd.cpp code:
#include "FactoringProgramH.h"
#include <stdio.h>
#include <iostream>
Factoring::Factoring(int FirstCoefficent=0, char FirstOperator='+',
int SecondCoefficent=1, char SecondOperator='+', int 3rdExpression=1)
: m_FirstCoefficent(FirstCoefficen), m_FirstOperator(FirstOperator),
m_SecondCoefficent(SecondCoefficent), m_SecondOperator(SecondOperator),
m_3rdExpression(3rdExpression);
{
}
int Factoring::InitialMessage()
{
std::cout << "Ok right now your expression is looking like: "
<< FirstCoefficent << "x^2 " << FirstOperator << " " << SecondCoefficent
<< " x" << SecondOperator << " " << 3rdExpression;
}
Your code has several small errors. Here is a version that works (you can compare and see what I had to change). A summary of the changes are:
default parameter values should be in the header file (*.h);
you cannot start variable/argument names with numbers;
int InitialMessage() doesn't return anything, so I changed it to void InitialMessage();
when you initialize fields in a constructor, the last field cannot end with a semi-colon;
fixed the most vexing parsing (per #RSahu comment) in main.cpp.
FactoringProgram.h
#ifndef FactoringProgram_h
#define FactoringProgram_h
#include <stdio.h>
#include <iostream>
class Factoring
{
private:
int m_FirstCoefficent;
char m_FirstOperator;
int m_SecondCoefficent;
char m_SecondOperator;
int m_3rdExpression;
public:
Factoring(int FirstCoefficent = 0, char FirstOperator = '+',
int SecondCoefficent = 1, char SecondOperator = '+', int thirdExpression = 1);
void InitialMessage();
};
#endif
FactoringProgram.cpp
#include "FactoringProgram.h"
Factoring::Factoring(int firstCoefficent, char firstOperator, int SecondCoefficent, char SecondOperator, int thirdExpression) :
m_FirstCoefficent(firstCoefficent),
m_FirstOperator(firstOperator),
m_SecondCoefficent(SecondCoefficent),
m_SecondOperator(SecondOperator),
m_3rdExpression(thirdExpression)
{}
void Factoring::InitialMessage()
{
std::cout << "Ok right now your expression is looking like: "
<< m_FirstCoefficent << "x^2 " << m_FirstOperator << " " << m_SecondCoefficent
<< " x" << m_SecondOperator << " " << m_3rdExpression;
}
main.cpp
#include <stdio.h>
#include <iostream>
#include "FactoringProgram.h"
int main()
{
Factoring Problem1;
Problem1.InitialMessage();
return 0;
}
To this error substitute:
Factoring Problem1();
by:
Factoring Problem1 = Factoring();
The problem is that the compiler is interpreting this line as a function declaration rather than a variable declaration. AS mentioned in the comments, this is known as the most vexing parser problem.
Obs: The code you posted contain many more minor errors.
You should define Factoring() without params and I used headers in FactoringProgram.h
FactoringProgram.h
#include <stdio.h>
#include <iostream>
class Factoring
{
private:
int m_FirstCoefficent;
char m_FirstOperator;
int m_SecondCoefficent;
char m_SecondOperator;
int m_3rdExpression;
public:
Factoring();
Factoring(int,char,int,char,int);
int InitialMessage();
};
#endif
FactoringProgram.cpp
#include "FactoringProgram.h"
int main()
{
Factoring Problem1 = Factoring();
Problem1.InitialMessage();
system("pause");
return 0;
}
FactoringProgram2nd.cpp
#include "FactoringProgram.h"
Factoring::Factoring()
{
*this = Factoring(0, '+', 1, '+', 1);
}
Factoring::Factoring(int FirstCoefficent = 0, char FirstOperator = '+',int SecondCoefficent = 1, char SecondOperator = '+', int _3rdExpression = 1) : m_FirstCoefficent(FirstCoefficent), m_FirstOperator(FirstOperator),m_SecondCoefficent(SecondCoefficent), m_SecondOperator(SecondOperator),m_3rdExpression(_3rdExpression)
{
}
int Factoring::InitialMessage()
{
std::cout << "Ok right now your expression is looking like: "
<< m_FirstCoefficent << "x^2 " << m_FirstOperator << " " << m_SecondCoefficent
<< " x" << m_SecondOperator << " " << m_3rdExpression;
return 0;
}
I am learning about functions and classes, and wrote my own code. I used the constructor to just initialize the variables. I have a function that is supposed to get the info I initialized with the constructor and allow me to display it. However, it doesn't want to work. I am not really sure what I am doing wrong. My error code says that I have unresolved externals because of my "void" function. I thought my function was not returning anything but rather just displaying the input it got from the initialization of the constructor.
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
class Berries {
string Nameofberries;
int Price;
public:
Berries (string N,int B)
{
Nameofberries = N;
Price = B;
}
void GetBerryInfo(const Berries& B)
{
cout << B.Nameofberries << endl;
cout << B.Price << endl;
}
};
void GetBerryInfo (const Berries& B);
int main ()
{
Berries Berryinfo1( "Raspberries", 7);
cout << GetBerryInfo;
system("pause");
return 0;
}
There are several mistakes.
void GetBerryInfo(const Berries& B)
{
cout << B.Nameofberries << endl;
cout << B.Price << endl;
}
should be
void GetBerryInfo()
{
cout << Nameofberries << endl;
cout << Price << endl;
}
==================================================================
void GetBerryInfo (const Berries& B);
should be removed.
==================================================================
cout << GetBerryInfo;
should be
Berryinfo1.GetBerryInfo();
==================================================================
All computer langauges are fussy, you have to get the details right, as well as understand the concepts.
This will do what you wanted:
# include <iostream>
# include <iomanip>
# include <string>
using namespace std;
class Berries {
string Nameofberries;
int Price;
public:
Berries (string N,int B)
{
Nameofberries = N;
Price = B;
}
void GetBerryInfo()
{
cout << Nameofberries << endl;
cout << Price << endl;
}
};
int main ()
{
Berries Berryinfo1( "Raspberries", 7);
Berryinfo1.GetBerryInfo();
system("pause");
return 0;
}
A couple of points on your mistakes:
GetBerryInfo() was declared inside the class. You don't need to re-declare it in the global scope. That 2nd declaration should be removed.
To be invoked, functions (like GetBerryInfo) must have () at the end of them like so: GetBerryInfo().
There is no point for GetBerryInfo() to take Berries as a paremeter. It is a member function that is part of the class Berries. It has access to all data members of a Berries instance already.
You don't need to use cout here: cout << GetBerryInfo; because the function body already sends the data members to cout. This function returns void so it doesn't make sense to send this to cout anyway.
I'm trying to learn C++ and have this small beginner question:
why does the standardize function not modify its inputs?
To help with the answers, I have posted an executing code at Coliru
here
and the sources of my program below.
Referring to the code, the question would be: why isn't what's
printed after outside the same as what's printed after inside?
#include <cstdlib>
#include <ctime>
#include <algorithm> // std::copy
#include <iostream>
using namespace std;
void standardize(const int n,const float x[],float ave,float sct){
float acc=0.0f,sum=0.0f;
sum=std::accumulate(x,x+n,0.0f);
ave=sum/(float)n;
std::for_each(x,x+n,[&](const float d){acc+=(d-ave)*(d-ave);});
sct=std::sqrt(acc/(float)(n-1));
std::cout << "inside" << std::endl;
std::cout << ave << std::endl;
std::cout << sct << std::endl;
return;
}
int main(){
const int n=1024;
float a2[n];
float part0=0.0f,part1=0.0f;
std::srand(std::time(0));
for(int i=0;i<n;i++) a2[i]=std::rand()/(float)RAND_MAX;
standardize(n,a2,part0,part1);
std::cout << "outside" << std::endl;
std::cout << part0 << std::endl;
std::cout << part1 << std::endl;
}
You are passing ave and sct by values. Your standardize method modifies copies of those arguments, letting unchanged the original ones declared in main()
Consider passing them by reference:
void standardize(const int n,const float x[],float& ave,float& sct)