Assigning iterator and integer in same statement

[shawnlau]

Why can't you declare and assign an integer with an iterator using the comma operator?

  #include <vector>
#include <iostream>

using namespace std;

class foo{
public:
	vector<int> m_bar;
	
};



int main(){

	foo a;
	a.m_bar.resize(10);

	//this is fine with the comma operator
	for (char a = 'c', int i = 0; i < 5; i++, a++)
		;

	// yet this is not fine with comma operator

	for (int i = 0, vector<int>::iterator iter = a.m_bar.begin();
		iter != a.m_bar.end(); iter++, i++)
		;

	return 0;
}

But this will work:

#include <vector>
#include <iostream>

using namespace std;

class foo{
public:
	vector<int> m_bar;
	
};



int main(){

	foo a;
	a.m_bar.resize(10);

	//this is fine with the comma operator
	for (char a = 'c', int i = 0; i < 5; i++, a++)
		;


	int i = 0;
	for (vector<int>::iterator iter = a.m_bar.begin();
		iter != a.m_bar.end(); iter++, i++)
		;

	return 0;
}

[MaxterTheTurtle]

I would look elsewhere in your code, because I cannot compile this segment of code:

for (char a = 'c', int i = 0; i < 5; i++, a++);

The first part of the loop is throwing errors, because it evaluates to something like this.

char a = 'c', int i = 0;

The problem is that you can only declare/initialize two variables of the same type on one line:

int a = 0, i = 32;

Thus, you can only declare/initialize e both the char and the int like:

char a = 'c';
int i = 32;

I imagine that the same goes for the iterator.

[shawnlau]

You're right. You can only declare one variable in the for statement, although you can assign multiple.