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golang 字符串比较
字符串比较， 可以直接使用 == 进行比较， 也可用用 strings.Compare 比较
go 中字符串比较有三种方式：
==比较strings.Compare比较strings.EquslFold比较
#### 代码示例
```go
fmt.Println("go"=="go")
fmt.Println("GO"=="go")
fmt.Println(strings.Compare("GO","go"))
fmt.Println(strings.Compare("go","go"))
fmt.Println(strings.EqualFold("GO","go"))
上述代码执行结果如下：
true
false
-1
0
true
Compare 和 EqualFold 区别
EqualFold是比较UTF-8编码在小写的条件下是否相等，不区分大小写
// EqualFold reports whether s and t, interpreted as UTF-8 strings, // are equal under Unicode case-folding. func EqualFold(s, t string) bool
- 要注意的是
Compare函数是区分大小写的，==速度执行更快
// Compare is included only for symmetry with package bytes. // It is usually clearer and always faster to use the built-in // string comparison operators ==, <, >, and so on. func Compare(a, b string) int
忽略大小写比较
有时候要忽略大小写比较, 可以使用strings.EqualFold 字符串比较是否相等
源码实现
// EqualFold reports whether s and t, interpreted as UTF-8 strings,
// are equal under Unicode case-folding, which is a more general
// form of case-insensitivity.
func EqualFold(s, t string) bool {
for s != "" && t != "" {
// Extract first rune from each string.
var sr, tr rune
if s[0] < utf8.RuneSelf {
sr, s = rune(s[0]), s[1:]
} else {
r, size := utf8.DecodeRuneInString(s)
sr, s = r, s[size:]
}
if t[0] < utf8.RuneSelf {
tr, t = rune(t[0]), t[1:]
} else {
r, size := utf8.DecodeRuneInString(t)
tr, t = r, t[size:]
}
// If they match, keep going; if not, return false.
// Easy case.
if tr == sr {
continue
}
// Make sr < tr to simplify what follows.
if tr < sr {
tr, sr = sr, tr
}
// Fast check for ASCII.
if tr < utf8.RuneSelf {
// ASCII only, sr/tr must be upper/lower case
if 'A' <= sr && sr <= 'Z' && tr == sr+'a'-'A' {
continue
}
return false
}
// General case. SimpleFold(x) returns the next equivalent rune > x
// or wraps around to smaller values.
r := unicode.SimpleFold(sr)
for r != sr && r < tr {
r = unicode.SimpleFold(r)
}
if r == tr {
continue
}
return false
}
// One string is empty. Are both?
return s == t
}
通过源码可看到 if 'A' <= sr && sr <= 'Z' && tr == sr+'a'-'A' 可以看到不区分大小写的实现。
看个完整测试代码：
// Golang program to illustrate the
// strings.EqualFold() Function
package main
// importing fmt and strings
import (
"fmt"
"strings"
)
// calling main method
func main() {
// case insensitive comparing and returns true.
fmt.Println(strings.EqualFold("Geeks", "Geeks"))
// case insensitive comparing and returns true.
fmt.Println(strings.EqualFold("computerscience", "computerscience"))
}
执行结构
true
true
