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Language: C++
Expertise: Beginner
Oct 16, 1998



Building the Right Environment to Support AI, Machine Learning and Deep Learning

The Scope of A Local Loop Counter

C++ allows you to declare variables wherever you need them, thus enabling immediate initializations. A good example is a loop counter. It can (and should) be declared inside a for-statement:
void f() 
for (int i = 0; i < 10; i++) // i declared and initialized inside a for-statement
		cout << i <<endl; //output 0 to 9
int *p = i; //compilation error, i no longer exists. It was allowed in earlier stages
In earlier stages of C++, a local variable declared this way remained accessible in its enclosing block. This was a source for bugs and name hiding. Consequently, the standard has been revised to fix this loophole, so to speak, and local variables created this way are inaccessible outside the for-statement in which they were declared. In the example above, i is inaccessible outside the loop.
Danny Kalev
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