Understanding Byte Assignment Error: Cannot Assign []byte to String

In your attempt to read files within a folder, you encountered the error "cannot assign []byte to z (type string) in multiple assignment" when attempting to read the contents of a file. Let's delve into the reason behind this error.

Understanding Multiple Assignment

When multiple variables are assigned values in a single line, as in your code:

z, err := ioutil.ReadFile(z)

Each variable on the left side of the assignment operator receives a corresponding value returned by the function. In this case, the ioutil.ReadFile function returns two values: []byte (binary data) and error.

Assigning Bytes to Strings

The problematic part is attempting to assign the []byte (binary data) returned from ioutil.ReadFile to the z variable, which is declared as a string. This is where the error arises because z is expecting a string value, not binary data.

Solution

To resolve this error, you have two options:

1. Convert the []byte to a string using the string() function:

buf, err := ioutil.ReadFile(z)
if err != nil {
    log.Fatal(err)
}
z = string(buf)

2. Declare z as a []byte instead of a string:

var z []byte
z, err := ioutil.ReadFile(z)

Working with Binary Data

While converting binary data to strings is possible, it's often preferable to work directly with the binary data itself. This avoids unnecessary conversion and preserves the original format of the data.