Function parameters are constants by default. Trying to change the value of a function parameter from within the body of that function results in a compile-time error. This means that you can’t change the value of a parameter by mistake. If you want a function to modify a parameter’s value, and you want those changes to persist after the function call has ended, define that parameter as an in-out parameter instead.
func add(x: Int, y: Int) -> Int
{
x=7 error: Can not assign to value x, x is let constant
return(x+y)
}
func add(x: inout Int, y: Int) -> Int
{
x=7
return(x+y)
}
func add(x: Int, y: Int) -> Int
{
x=7 error: Can not assign to value x, x is let constant
return(x+y)
}
func add(x: inout Int, y: Int) -> Int
{
x=7
return(x+y)
}
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