logical operators

ok

now here's my confusion logical operators

Code:

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int i, j,k;
i=10; j=1; k=-2;
printf("%d",  !i < j);    //what does  !i  mean???  //
printf("%d",  !!i < !j);    //  what does !!i  mean ???  //
printf("%d", i && j || k);    //  what is the result asking for ?? //
printf("%d", i < j || k);    //    again, there's no if clause asking for comparison, so what does the result ask for??  //

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I compiled code and ran and all the results were 1.
Is that a 1 meaning TRUE for the relation between 2 values??
I am just so confused on the use of these logical operators.

Gimme loops or if-else statements anytime!!


:(

explained recently on the c++ board. have a look for a thread called AND,OR and NOT or something like that.

Sorry, Stone, read the post on AND , OR , & NOT and don't get it.
Please help.
I guess what is confusing me is using < or > with AND OR NOT
and getting an evaluation.

So.........

int i, j,k;
i=10; j=1; k=-2;
printf("%d", !i < j);

Is this saying, NOT i < j
thus NOT 10 < 1
thus TRUE
yields TRUE and TRUE is a result value of 1 ???


printf("%d", !!i < !j);

Is this saying, NOT(NOT i) < NOT j
thus NOT (NOT 10) < NOT 1
thus 10 < NOT 1
thus TRUE
yields TRUE, thus value of 1 ????

printf("%d", i && j || k);

Is this saying, (i AND j) OR k
thus (10 AND 1) OR -2
thus TRUE OR TRUE
yields TRUE, thus value of 1 ????

printf("%d", i < j || k);

Is this saying, (i < j) OR k
thus (10 < 1) OR k
thus FALSE OR TRUE
yields TRUE, thus value of 1 ????s

Priority of operators, Inequality comes before logical AND (&&) logical OR (||) and although my text Im referencing from I pretty sure NOT comes before logical AND. Now referring back to your first post,


i=10; j=1; k=-2;

printf("%d", !i < j);

It tests ( i < j ) or (10 < 1)
this is no so it returns zero
then NOT Zero is one
so it prints one.

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printf("%d", !!i < !j);
!!i is the same as i
Not a 100% sure on what !j does but i think because j == 1
"j" now becomes zero. So the whole thing becomes

i<!j == 10<0 == 0


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try other values and play around with the logical operators. If you need more help post a reply

In fact, NOT (!) comes before inequalities (<, >, <= etc) it is a unary operator.