Is this while condition is valid?? :-

Question

#include<iostream>
using namespace std;
int main()
{int a;
while(a<7)
{}
return 0;
}

Answer 1

Not valid. a does not have any value.

#include<iostream>
using namespace std;
int main()
{int a=5; //initializing a
while(a<7)
{}
return 0;
}

//Now the code would run in an infinite loop

#include<iostream>
using namespace std;
int main()
{int a=5;
while(a<7)
{a++;}
return 0;
}

//Now the code would run but give no output

#include<iostream>
using namespace std;
int main()
{int a=5;
while(a<7)
{a++;
cout <<a;}
return 0;
}

//Now codes runs and prints 67

Answer 2

it is not returning anything.

Answer 3

it is valid condition, but because there is nothing in the while block you get an infinite loop.
-try increasing a in the while loop
-also print something so that you see some output
eg:
cout<<a++;

[edit]
also 'a' needs bring initialized otherwise will be a random number, maybe greater than 7.

Answer 4

the condition is valid buy it is nonsense because a is not initialised and count of loops is not defined.The curly brackets are wasted on other hand the semicolon is missing and there is no defined incresing statement.