Use of command line parameters, use of goto labels, and local variable declaration in the For Loop

/*
* Test command line parameters

*/
# Include <iostream>
Using namespace STD;

Int main (INT argc, char * argv []) {
 
Cout <argv [0] <Endl; // The first parameter is the applicationProgramName
Cout <argc <Endl;
 
}

 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

/*

* Use the Goto tag

*/

# Include <iostream>
Using namespace STD;

Int main (){
 
Int I = 4;
Flag:
Cout <I <Endl;
If (I! = 0 ){
I = 0;
Goto flag;
}
Return 0;
}

 

~~~~~~~~~~~~~~~ Strange local variables are not initialized ~~~~~~~~~~~~~~~~ ·

 

# Include <iostream>
Using namespace STD;

Int main (){
 
Int J;
For (INT I = 0, j = 0; I <5; I ++, J ++ );
 
Cout <j <Endl;

}

Here, if int I = 0 is used in the for loop, the compiler considers that J is only a local variable. The output J value is also a random number.

The reason is that the statement int I = 0, j = 0 is interpreted as declaring two local variables I, J at the same time, and assigning the initial value.

J declared before the for loop is blocked.