Operator '==' cannot be applied to operands of type int and string using Asp.net Mvc

Question

I am creating a simple inventory system in Asp.net MVC

I have got an error at this line below

int db_product = db.products.First(e => e.id == m.barcode_id);

One of those values (id or barcode_id) is an int, and one is a string, as stated by the error message. So you cannot compare the two. You will need to cast the string to an int, or the int to a string, to be able to compare them. — NibblyPig
– NibblyPig, Commented Oct 23, 2019 at 13:29
yes e.id should be interger. barcode_id is string . so how to cast it sir — jaya priya
– jaya priya, Commented Oct 23, 2019 at 13:30
The simplest way is with int.Parse(m.barcode_id) but it depends on what you expect the ID to be. It would always have to be a number for that to work. This might not be compatible with your database context if you're using entity framework for example. — NibblyPig
– NibblyPig, Commented Oct 23, 2019 at 13:31
int db_product = db.products.First(e => e.id.ToString()== m.barcode_id); Since you said barcode_id is a string, just convert your e.id to string and compare. — N.S
– N.S, Commented Oct 23, 2019 at 13:33
int db_product = db.products.First(e => e.id.ToString() == m.barcode_id); i did sir but i got the Error Cannot implicitly convert type to Int — jaya priya
– jaya priya, Commented Oct 23, 2019 at 13:37

nurdyguy · Accepted Answer · 2019-10-23 14:02:03Z

2

As the comments noted, the error really says it all. One of your variables is an int and one is a string so they cannot be directly compared. You need to convert either the int to a string or the string to an int, I would do the latter in this case but both can work. Something like this could work:

var db_product = db.products.First(e => e.id.ToString() == m.barcode_id)

edited Oct 23, 2019 at 14:02

answered Oct 23, 2019 at 13:52

nurdyguy

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4 Comments

jaya priya Over a year ago

if i write it like this way db.products.First(e => e.id.ToString() == m.barcode_id) it is working sir but int db_product = db.products.First(e => e.id.ToString() == m.barcode_id); db_product.qty = db_product.qty - m.qty; if i write it int db_product = like this error i need this variable to do the calucation db_product.qty = db_product.qty - m.qty; like this

nurdyguy Over a year ago

It is hard to understand what you need based on that comment but why can't you do db_product.qty = db_product.qty - m.qty; on the next line? The first line find the product you need and the next calculates the new qty value.

jaya priya Over a year ago

yes sir. The first line find the product next calculates the new qty value.

nurdyguy Over a year ago

Oh, actually your first problem is that you used int db_product but the thing you are getting is not an int, it is a product from your products table. Change the int db_product to be var db_product as I just did in my edit, then add the second line where you do the subtraction.

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