C/C++ Can someone explain why this isn't an infinite loop? (C++)

[PNGeng]

This was a question from my C++ midterm.

I see an infinite loop, but the correct answer is 12. Can anyone explain this?

Question: What is the value of i after the loop exits?

int i;
for(i=0; i < 10; i++)
i+=3;
i=1;

 

[DaleSwanson]

Think like a compiler; ignore white space; treat semicolons as ends of lines.

 

[jhae2.718]

I'm assuming that should be:

int i;
for(i=0; i < 10; i++)
i+=3;
i[b]+=[/b]1;

as otherwise the answer would be 1.

The best way is to step through the code by hand:

Iteration    Value     i<10?
1              3         yes    // starts at zero then adds 3
2              7         yes    // incremented by 1, then add 3
3              11         no    // same, then stops at next test

then add one to get 12.

 

[dimensionless]

The loop ends when i = 10 or i > 10. This condition is set in the line:

for(i=0; i < 10; i++)

 

[rcgldr]

Without any braces, the for loop only includes the next statement. The equivalent code with braces would be:

int i;

    for(i=0; i < 10; i++)
    {
        i+=3;
    }

    i=1;