nonstandard extension used : 'var' : loop control variable declared in the for-loop is used outside the for-loop scope; it conflicts with the declaration in the outer scope
When compiling with /Ze, a variable declared in a for loop was used after the for-loop scope. A Microsoft extension to the C++ language allows this variable to remain in scope, and C4288 reminds you that the first declaration of the variable is not used.
The following sample generates C4288:
void main() { int i = 0; // not used in this program for (int i = 0 ; ; ){} i++; // C4288, using for-loop declaration of i }