C# get first byte index from a byte array

Question

I have a byte Array that contains the char '%' (25 hex, 37 decimal). I would like to get the index of this byte, however, none of these methods work, and -1 is returned. How to get the index of a specific byte in a byte array?

int byteIndex = Array.IndexOf(bytesDataArray, '%');
int byteIndex = Array.IndexOf(bytesDataArray, 37);
int byteIndex = Array.IndexOf(bytesDataArray, 0x25);

Bytes and chars are different types. What is actually in the byte array? — Luaan
– Luaan, Commented May 17, 2021 at 10:28
Array.IndexOf has overloads which take object, and so you need to make sure that the data type of the thing you're searching for is correct. You've got an array of bytes, but you're passing a char, and then two ints. If you make sure that you always pass a byte, everything works — canton7
– canton7, Commented May 17, 2021 at 10:28
"I have a byte Array that contains the char" - A byte array contains bytes, not chars. You should separate those two concepts in your mind. I suspect that if you search for a byte instead of an int or a char, it will work... — Jon Skeet
– Jon Skeet, Commented May 17, 2021 at 10:28
@canton7: There are overloads of Array.IndexOf that are generic, but if those fail, it'll fall back on the non-generic one, which I believe is what's happening here. — Jon Skeet
– Jon Skeet, Commented May 17, 2021 at 10:29
@JonSkeet Spotted and corrected mere seconds before your comment :) — canton7
– canton7, Commented May 17, 2021 at 10:29

Luaan · Accepted Answer · 2021-05-17 10:29:54Z

2

You're trying to find an int value of 37 in a byte array. Byte arrays don't contain ints. You need to do a type cast:

int byteIndex = Array.IndexOf(bytesDataArray, (byte)37);

answered May 17, 2021 at 10:29

Luaan

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1 Comment

Jaume Over a year ago

oh sure, casting was the solution. Thanks :)

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