On the operating mechanism of cout in C + + _c language

Copy Code code as follows:

#include <iostream>
using namespace Std;
int Hello1 ();
int Hello2 ();

int main ()
{
int A, B;
cout<< "A=" <return 1;
}
int Hello2 ()
{
cout<< "Hello2" <<endl;
return 2;
}

The final output is:
Hello2
Hello1
A=1 b=2

It's a bit hard to figure out, and it's a plausible explanation on the Web: the Order of operations for cout streams is to read the buffer from right to left and then output from left to right. So when it reads from the right to the left, it touches the function, of course, executes the function first, then reads the function return value into the buffer and then ... is the output from the left.

According to this explanation, there are several experimental procedures that can deepen understanding.

Program 1:

Copy Code code as follows:

#include <iostream>
using namespace Std;
int main ()
{
int b[2]={1,2};
int *a=b;
cout<<*a<< "" <<* (a++) <<endl;
return 0;
}

The output is: 2 1.
Interpretation: first read into the * (a++), for a++, is read into the buffer, its own, so, at this time the buffer of a is 1,. Read the *a again, at this time a has been increased, so read into the buffer is 2.

Program 2:

Copy Code code as follows:

#include <iostream>
using namespace Std;
int main ()
{
int i=5;
cout<<i<< "" << (i++) << "" << (++i) <<endl;
return 0;
}

Output is: 7 6 6
Explanation: From right to left, first (++i), that is, the first increment, then read into the buffer, 6. Again (i++), that is, read into the buffer first, to 6, and then increase itself. The last is I, read into the buffer is 7.