golang array modification

In Golang, an array is a fixed-length, ordered collection containing elements of the same type. However, in actual development we are likely to encounter situations where we need to modify array elements.

First of all, it needs to be clear that in Golang, arrays are value types. This means that if we assign an array to another array or pass an array as a parameter, we are actually passing a copy of the array, not the original array itself. Therefore, if we want to modify an array element, we need to modify the original array, not its copy.

The most basic way to modify an element in an array is to reference the element in the array by index and assign a new value:

arr := [3]int{1, 2, 3}
arr[0] = 4

In the above example, we created an integer of length 3 Array, change the first element from 1 to 4. This method is relatively simple and easy to understand, but sometimes we need to operate on the entire array, in which case we need to use the array pointer.

In Golang, the pointer type of an array is a pointer, pointing to the first element of the array. You can get the pointer of the array through the "&" operator:

arr := [3]int{1, 2, 3}
ptr := &arr[0] //指向arr数组的第一个元素

In the above example, we created an integer array of length 3 and assigned the pointer of its first element to ptr. Next, we can modify the entire array by modifying the value pointed to by the ptr pointer:

*ptr = 4 //修改第一个元素的值
*(ptr+1) = 5 //修改第二个元素的值
*(ptr+2) = 6 //修改第三个元素的值

In the above example, we use the "" operator, which means taking the value pointed to by the pointer. value. Through the " " operator, we can move to any position in the array, and then modify the value of that position through the "" operator.

In addition, there is a built-in function in Golang specifically for processing arrays - "copy". This function copies elements from one array to another and returns the number of elements actually copied.

arr1 := [3]int{1, 2, 3}
arr2 := [3]int{} //创建一个长度为3的空数组
num := copy(arr2[:], arr1[:]) //将arr1的元素复制到arr2中，并返回复制的元素数量

In the above example, we created two integer arrays of length 3, copied the elements in arr1 to arr2, and returned the number of copied elements. It should be noted that we use the "[:]" operator to obtain a slice of the entire array, thereby copying the entire array to another array.

In general, there are many ways to modify array elements in Golang. In simple cases, we can directly reference elements in the array by index and assign new values. In more complex cases, we can use array pointers to operate, or use the built-in function "copy" to copy one array to another array. Either way, be aware that arrays are value types and you need to modify the original array rather than its copy.

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