variable gets undefined behaviour out of the loop body

[demir]

Hi,

I am writing C++ program on Visual Basic first, once it is compiled I will port it into STM32 Cube IDE environment. I wrote a simple for loop. When I run this code, I get very strange value for z out of the loop that is 1971940899.

You can see the terminal output as below.

when z is equal to 10, the loop will be broken out
5
when z is equal to 10, the loop will be broken out
6
when z is equal to 10, the loop will be broken out
7
when z is equal to 10, the loop will be broken out
8
when z is equal to 10, the loop will be broken out
9
when z is equal to 10, the loop will be broken out
1971940899

Could you please help me resolve ?

Thanks.

for(int z=5;z<15;z++)
{

    cout<<"when z is equal to 10, the loop will be broken out\n";
    if(z==10)
    {
    break;
    }
    cout<<z<<endl;
}
cout<<z<<endl;

[Tesla DeLorean · Accepted solution]

Because it's out-of-scope, and may be a register or stack variable

{ // SCOPE A
  int z;
  for(z=5;z<15;z++)
  { // SCOPE B
    cout<<"when z is equal to 10, the loop will be broken out\n";
    if(z==10)
    {
    break;
    }
    cout<<z<<endl;
  } // END SCOPE B
  cout<<z<<endl;
} // END SCOPE A