golang cast

With the wide application of Golang in the Internet field, there is an increasing demand for Golang forced type conversion. Casting is the conversion of a value of one data type to a value of another data type, and the converted value may be truncated or lose precision. This article will introduce the relevant knowledge of Golang forced type conversion from the following four aspects.

1. Syntax of forced type conversion

In Golang, for different data types, we can convert them to other types through forced type conversion. The syntax is:

T(expression)

Among them, T represents the target type, and expression represents the expression that needs to be cast.

For example, convert an int type variable to a float32 type variable:

var a int = 10
var b float32 = float32(a)

2 .Forced type conversion between basic data types

In Golang, forced type conversion between basic data types is relatively simple. Common type conversions are as follows:

int is converted to float32 or float64 Type:

var a int = 10
var b float32 = float32(a)

float32 or float64 converted to int type:

var a float32 = 10.5
var b int = int(a)

Convert string to int type:

var a string = "100"
var b int, err = strconv.Atoi(a)
if err == nil {

fmt.Println(b)

}

int is converted to string type:

var a int = 100
var b string = strconv.Itoa (a)

It should be noted that when performing data type conversion, precision loss or data truncation may occur. For example, when converting a float64 type decimal to an int type, data truncation may occur, resulting in inaccurate results.

3. Casting of structures and pointers

In Golang, casting between structures and pointers requires the use of pointer types in the unsafe package. For example, convert a structure pointer to int type:

import "unsafe"

func main() {

type Example struct {
    x int
    y float32
}

var example Example
example.x = 10
example.y = 10.5
examplePtr := unsafe.Pointer(&example)
exampleInt := uintptr(examplePtr)
fmt.Println(exampleInt)

}

above In the example, unsafe.Pointer(&example) converts the pointer of the structure Example into a pointer of type unsafe.Pointer, and then converts it into a value of type uintptr. The final output result is the starting address of the structure example.

It should be noted that using the unsafe package for forced type conversion will bring great risks, because the functions in the unsafe package will bypass the type checking and safety mechanism of the Go language, which may cause program exceptions. Issues such as behavior or memory leaks.

4. Forced type conversion between slices and arrays

In Golang, forced type conversion between slices and arrays is relatively common, and type conversion can be performed directly. For example, convert an array of type int to a slice of type float32:

var arr [5]int = [5]int{1, 2, 3, 4, 5}
var slice [] float32 = ([]float32)(unsafe.Pointer(&arr))

In the above example, use unsafe.Pointer(&arr) to convert the pointer of the array arr to unsafe.Pointer type pointer, and then convert it to a slice of type []float32, and the final output result is [1 2 3 4 5].

It should be noted that cast type conversion between slices and arrays is a very common operation, but it should also be used with caution. Because the underlying memory structures of slices and arrays are different, forced type conversion may have an impact on the memory structure, causing program crashes or data exceptions.

Summary

This article introduces the relevant knowledge of Golang forced type conversion, including conversion between basic data types, conversion of structures and pointers, conversion of slices and arrays, etc. It should be noted that although forced type conversion is necessary in actual development, you must also pay attention to usage scenarios and precautions to avoid possible risks and problems.

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