Expert: Eddie - 8/7/2006

Question

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Followup To

Question -
please explain the difference between these 2 segments of the C code:
if (a & b)
     flag = 0;
 else flag = 1;

if (a && b)
     flag = 0;
 else flag = 1;


Answer -
Hello simon, thank you for the question.

The first segment of code checks if a bitwise "anded" with be is a non zero value and assigns a variable based on the answer. The second segment of code checks to see if both the variables are non zero, like if a and b are both equal to true, and assigns a variable based on the answer.

I hope this information was helpful.

- Eddie



Hi, here's another one for you Eddie.

which of these C statements are wrong syntactically (i.e. would generate a compiler error as the syntax is wrong), and why?

1. int k, h;
2. float k = 0.0 + p;
3. if (n = 4) n = 0;
4. #define MAX 10000*5
5. while (m) { k++; m--}
6. char c, h

thanx

Answer
Hello again Simon, thank you for the question.

3 is incorrect. When you check to see if something equals a value, you use 2 equals signs. The correct syntax is:

if (n == 4) n = 0;

Feel free to ask another question if you need clarification on anything else.

- Eddie