Please why is it printing out "they are equal "

Question

https://code.sololearn.com/W5iFaoJWP6qz/?ref=app
why isn't it printing out b since a isn't assigned to b

Answer 1

use if (a==b) instead of if (a=b)

if (a=b) will assign b to a, instead of doing a comparison.

Answer 2

It's because it's failing to open the file called 'file'.

fopen returns null on failure, which is equal to zero. In an if statement, 0 means false, and non-zero values mean true.

if (fp = fopen("file", "w"))
{
console.log("yes") // File to open the file.
}
else
{
console.log("no")// Process the file.
}

On failing to open a file:
if (fp = fopen("file", "w")) evaluates to:
if (fp = null) which evaluates to:
fp = null; if (0) which leads to the else statement being actioned.
if (0) can be thought of as if (false)

On succeeding to open a file:
if (fp = fopen("file", "w")) evaluates to:
if (fp = 4467544) or some such value, which evaluates to:
fp = 4467544; if (4467544) which can be thought of as:
fp = 4467544; if (true)

Answer 3

Xan:
fopen() doesn't not exist in javascript, until you define a custom so named function, as OP done in its last example code, by defining an empty fopen() function, which always return 'undefined' so, the condition is always false ^^

Answer 4

Apologies! Very late night. I was mixing up javascript and C! Thanks for pointing that out :-)

Answer 5

OK thanks xan

Answer 6

but why didn't it take note that it wasn't assigned.... why did it have to assign under if statement?

Answer 7

You might want to do something like this, in which case the assignment makes sense. A compiler doesn't have much intelligence. As long as your code parses correctly, it doesn't care about common sense!

if (fp = fopen("file", "w"))
{
// Process the file (file was opened for writing).
}
else
{
// Report an error (file could not be opened for writing).
}

Answer 8

k thanks again xan

Answer 9

I ran it here

Answer 10

https://code.sololearn.com/WHTDz52fP6fb/?ref=app

Answer 11

and it returned no

Answer 12

Apologies, I've updated my comment!

Answer 13

please I don't understand because it is running the else statement