英文:
Golang edit array of struts from main() to function
问题
希望你能帮忙，以下是我代码的简化版本。
基本上，我将一个结构体数组传递给floatInSlice()函数，其中要么向数组中添加一个新的结构体，要么将现有结构体的AudienceCategory.Sum增加1。
总体上都工作得很好，除了b.Sum = b.Sum+1这一行。
现在我知道，如果我想将一个对象作为指针而不是值传递，我需要使用*和&，但是我似乎无法让它工作，非常感谢任何帮助！
type AudienceCategory struct {
Cat int
Sum int
}
var counter = []AudienceCategory{}
func main() {
for i := 1; i < len(words); i++ {
counter = floatInSlice(category, counter)
if counter != nil {}
}
fmt.Printf("%v ", counter)
}
func floatInSlice(category int, counter *[]AudienceCategory) []AudienceCategory {
for _, b := range counter {
if b.Cat == category {
b.Sum = b.Sum+1
return counter
}
}
x := AudienceCategory{Cat: category, Sum: 1}
counter = append(counter, x)
return counter
}
编辑***********
最后终于搞定了，感谢大家的帮助！
func floatInSlice(category int, counter []AudienceCategory) []AudienceCategory {
for i := 0; i < len(counter); i++ {
if counter[i].Cat == category {
counter[i].Sum = counter[i].Sum+1
return counter
}
}
x := AudienceCategory{Cat: category, Sum: 1}
counter = append(counter, x)
return counter
}
英文:
hoping you can help below is a concise version of my code.
basically im passing an array of structs to floatInSlice() in which either a new struct gets added to the array or an existing struct AudienceCategory.Sum gets ++
all is generally working fine except for the b.Sum = b.Sum+1
Now I know that if I want to pass an obect as a pointer rather than value I need to use */& but I just cant seem to get it working, any help much appriciated!
type AudienceCategory struct {
Cat int
Sum int
}
var counter = []AudienceCategory{}
func main() {
for i := 1; i < len(words); i++ {
counter = floatInSlice(category,counter)
if counter != nil{}
}
fmt.Printf("%v ", counter)
}
func floatInSlice(category int, counter *[]AudienceCategory) []AudienceCategory {
for _, b := range counter {
if b.Cat == category {
b.Sum = b.Sum+1
return counter
}
}
x := AudienceCategory{Cat:category,Sum:1}
counter = append( counter, x)
return counter
}
EDIT ***********
got it working in the end thanks for the help guys
func floatInSlice(category int, counter []AudienceCategory) []AudienceCategory {
for i := 0; i < len(counter); i++ {
if counter[i].Cat == category {
counter[i].Sum = counter[i].Sum+1
return counter
}
}
x := AudienceCategory{Cat:category,Sum:1}
counter = append( counter, x)
return counter
}
答案1
得分: 1
当你在_, b := range counter中使用值范围时，b包含counter的每个元素的副本。所以你正在对一个丢失的副本求和，而不是对切片中的元素求和。
你应该使用以下代码：
func floatInSlice(category int, counter *[]AudienceCategory) []AudienceCategory {
for i, b := range *counter {
if b.Cat == category {
(*counter)[i].Sum = (*counter)[i].Sum+1
return counter
}
}
x := AudienceCategory{Cat:category,Sum:1}
counter = append( counter, x)
return counter
}
这样你就可以正确地对切片中的元素进行求和了。
英文:
When you use value range as in _, b := range counter, b contains a copy of each element of counter. So you are summing a copy that is lost, not the element in the slice.
You should use
func floatInSlice(category int, counter *[]AudienceCategory) []AudienceCategory {
for i, b := range *counter {
if b.Cat == category {
(*counter)[i].Sum = (*counter)[i].Sum+1
return counter
}
}
x := AudienceCategory{Cat:category,Sum:1}
counter = append( counter, x)
return counter
}
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