logical-operators

As a php neewbie , I try to read a lot of other people´s code in order to learn. Today I came across a line like this : if ( stripos($post_to_check->post_content, '[' . $shortcode) !== false ) I was wondering what is the difference between !==false and ==true If someone can explain that to me, It would be greatly appreciated. ..and if there is no real difference - what would be the reasons to use the quoted one over the other ?? PHP is a loosely typed language. == match the both values and === match the values as well as the data type of values. if (8 == '8') // returns true Above condition

I am getting an exception as I try to slice with a logical expression my Pandas dataframe. My data have the following form: df GDP_norm SP500_Index_deflated_norm Year 1980 2.121190 0.769400 1981 2.176224 0.843933 1982 2.134638 0.700833 1983 2.233525 0.829402 1984 2.395658 0.923654 1985 2.497204 0.922986 1986 2.584896 1.09770 df.info() <class 'pandas.core.frame.DataFrame'> Int64Index: 38 entries, 1980 to 2017 Data columns (total 2 columns): GDP_norm 38 non-null float64 SP500_Index_deflated_norm 38 non-null float64 dtypes: float64(2) memory usage: 912.0 bytes The command is the following: df[(

I was reading my textbook for my computer architecture class and I came across this statement. A second important distinction between the logical operators ' && ' and ' || ' versus their bit-level counterparts ' & ' and ' | ' is that the logical operators do not evaluate their second argument if the result of the expression can be determined by evaluating the first argument. Thus, for example, the expression a && 5/a will never cause a division by zero, and the expression p && *p++ will never cause the dereferencing of a null pointer. (Computer Systems: A Programmer's Perspective by Bryant and

While Learning compiler Optimisation, I write codes in C under Linux with GCC version gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5.1) To understant not a statement (nop) in C. I written two codes first y.c second x.c and generate their compiled assembly code using gcc -S option. Fist code y.c desktop:~$ cat y.c main() { int i=0; } desktop:~$ gcc -S y.c desktop:~$ Second code x.c desktop:~$ cat x.c main() { int i=0; /* Loops and if*/ while(0); for(;0;); if(0); /* Arithmetic Operations */ i * i; i / i; i - i; i + i; i % i; +i; -i; /* Comparison operators */ i == i; i != i; i < i; i > i; i >=

What is the difference between the | and || logical operators in MATLAB? I'm sure you've read the documentation for the short-circuiting operators , and for the element-wise operators . One important difference is that element-wise operators can operate on arrays whereas the short-circuiting operators apply only to scalar logical operands. But probably the key difference is the issue of short-circuiting. For the short-circuiting operators, the expression is evaluated from left to right and as soon as the final result can be determined for sure, then remaining terms are not evaluated. For

When I try this: $a = 1; $b = 2; print ($a && $b) . "\n"; The result is 2. Why? Quote perlop : The "||", "//" and "&&" operators return the last value evaluated (unlike C's "||" and "&&", which return 0 or 1). The resulting 2 is considered true by Perl, so that when you use the && operator in a logical condition, everything works as expected. The added bonus is that you can use the logical operators in other contexts as well: sub say_something { say shift || 'default'; } say_something('foo'); # prints 'foo' say_something(); # prints 'default' Or even as flow modifiers: my $param = shift || die

We know that logical-AND operator ( && ) guarantees left-to-right evaluation. But I am wondering if the compiler optimizer can ever reorder the memory access instructions for *a and b->foo in the following code, i.e. the optimizer writes instructions that try to access *b before accessing *a . (Consider both a and b to be pointers to memory regions in the heap.) if (*a && b->foo) { /* do something */ } One might think that && causes a sequence point, so the compiler must emit instructions to access *a before accessing *b but after reading the accepted answer at https://stackoverflow.com/a

This question already has an answer here: Logical operators in JavaScript — how do you use them? 2 answers When I type in browser's console: console.log(2 && 3) it results always with second number (in this case 3): 3 Can someone explain me why? If the left hand side of && evaluates as a false value, the whole expression evaluates as the left hand side. Otherwise it evaluates as the right hand side. 2 is a true value, so 2 && 3 is 3 . For comparison, try console.log(0 && 1) and console.log(false && "something") . The && logical operator will return the last value if all other values are truthy