Mark44 said:
Oh my god, you are correct. I never thought about that. Now I can at least move on. Never thought namespace std caused so much problem.Mark44 said:
Here's a test:yungman said:
const int size;char name[25];
name[25] = "alan";Made my dayMark44 said:
.Mark44 said:
#include<iostream>
using namespace std;
int main() {
cout << "Test.\n";
return(0);
}#include<iostream>
int main() {
using namespace std;
cout << "Test.\n";
return(0);
}#include<iostream>
int main() {
using std::cout;
cout << "Test.\n";
return(0);
}First question, it was a mistake, somehow I deleted it when I copied over.pbuk said:Here's a test:
Q1. Explain using the terms 'declaration' (or declare) and 'initialisation' (or initialise) why this code does not make sense:
C++:const int size;
Q2. `Give 2 reasons why this code doesn't work:
Made my dayC++:char name[25]; name[25] = "alan";
Yes I did! First one I forgot the 25. the second one is using the wrong =, can't do that with c-strings. Isn't that obvious?Mark44 said:
const int size = 25 inside the class, as member data, but you have to make it static, presumably because that value is intended to be shared among all the instances of the class.class Vec
{private:
int x, y, z;
static const int size = 25;
char name[size];
// etc.
};const int size = 25;), g++ gives me merely a warning message, not an error: in-class initialization of non-static data member is a C++11 extension.I am glad you are here. This is an extension YOUR thread! I just don't want to hijack your thread so I started my own. My VS is 2019.jtbell said:
#include <iostream>
#include <cstring>
using std::ostream;
using std::cout; using std::endl;
const int size = 25;
class Vec
{private:
int x, y;
char name[size];
public:
Vec(int x0, int y0, char *desc)
{ x = x0, y = y0;
strncpy_s(name, size, desc, size);
}
};
int main()
{ char vecA[size] = "vecA";
Vec a(1, 2, vecA);//This works
Vec b(2, 4, "vecB");//This doesn't work.
return 0;
}Already answered. See post #67. Again, please read what others and I write. It's disrespectful to us and wasteful of our time when we answer a question that you've asked, and you don't read the responses, and ask the same question again.yungman said:
char name[25];
name[25] = "alan";If that's the wrong =, is there another = that works? What's your second reason?yungman said:
yungman said:
To elaborate a bit on the statement in post #67:Mark44 said:
"vecB" doesn't have type char *. It implicitly has type const char *, because it makes no sense to change the value of a literal string.const char * to a function that declares a parameter to be char *. When you declare a parameter without specifying const, it signals to the compiler that the function might change the value of the parameter.const char *.char * (e.g. a char array that isn't declared as const) to a function that declares a parameter as const char *.)THANK YOUjtbell said:
Can you tell me which post #?jtbell said:
Please stop!yungman said:
#include <iostream>
#include <cstring>
using std::ostream;
using std::cout; using std::endl;
const int size = 25;
class Vec
{private:
int x, y;
char name[size];
public:
Vec(){ x = 0, y = 0;
strncpy_s(name, size, "Default", size);
cout << " [In Dconstructor], object created: " << name <<
"(" << x << "," << y << ") address: " << this << "\n\n";
}
Vec(const char*desc) { x = 0, y = 0;
strncpy_s(name, size, desc, size);
cout << " [In Constructor], object created: " << name <<
"(" << x << "," << y << ") address: " << this << "\n\n";
}
Vec(int x0, int y0, const char *desc){ x = x0, y = y0;
strncpy_s(name, size, desc, size);
cout << " [In Constructor], object created: " << name <<
"(" << x << "," << y << ") address: " << this << "\n\n";
}
Vec(const Vec& original)
{ x = original.x; y = original.y;
strncpy_s(name, size, "Temp", size);
cout << " [In Copy Constructor], object created: " << name <<
"(" << x << "," << y << ") address: " << this << "\n\n";
}
~Vec(){cout<<" Destroying "<<(*this).name<<", Address: "<<this<<"\n\n";}
Vec operator+(const Vec& right)
{ Vec sum;
sum.x = x + right.x; sum.y = y + right.y;
strncpy_s(sum.name, size, "sum", size);
cout <<" [In OP+]: " << sum.name << "(" << sum.x << "," << sum.y <<
") = " << (*this).name <<"(" << (*this).x << "," << (*this).y <<
") + " << right.name <<"(" << right.x << "," << right.y << ")\n\n";
return sum;
}
Vec& operator=(const Vec& rhs)
{x = rhs.x; y = rhs.y;
strncpy_s(name, size, rhs.name, size);
cout << " [In OP=]: " << rhs.name << "(" << rhs.x << "," << rhs.y <<
") is copied into " << name << "(" << x << "," << y << ")\n\n ";
return *this;
}
friend ostream& operator<<(ostream& out, const Vec& v)
{out << " [OP<<] c contains: " << v.name << "(" << v.x << "," << v.y << ")\n\n"; return out; }
};
int main()
{ Vec a(1, 2, "vecA");
Vec b(3, 4, "vecB");
Vec c("vecC");
c = a + b;
cout << c << "\n\n";
return 0;
}Hi MarkMark44 said:
The one you were replying to... #82.yungman said:
Oh good!, I need to edit my notes, I literally copy part of your post 82 into my notes. I thought you were talking about in your thread.jtbell said: