golang compare_frac_and_exp.go

Posted 2021-05-24

package main

import (
	"fmt"
)

const maxIdx = 16 // これより大きいとオーバーフローする

func frac(n int) int {
	if n == 0 {
		return 1
	}
	return n * frac(n-1)
}

func expotensial(x int) int {
	base := 1
	for i := 1; i <= x; i++ {
		base = base * x
	}
	return base
}

func main() {
	for i := 0; i < maxIdx; i++ {
		fmt.Printf("%d! = %d, %d^%d = %d\n", i, frac(i), i, i, expotensial(i))
	}
}

json [Golang] golang #golang #snippets中有用的片段

[ fmt ](https://golang.org/pkg/fmt/)
-------
Print any `type`(struct,maps,primitives) with the `key` name 

``` 
fmt.Printf("\n [key] :%+v \n", [value]) 

```

Print Error  

``` 
fmt.Errorf(" \nError: %s", err.Error()) 

```

[ log ](https://golang.org/pkg/log/)
-------------

Print any `type`(struct,maps,primitives) with the `key` name 

``` 
log.Printf("\n [key] :%+v \n", [value]) 

```


[ http  ](https://golang.org/pkg/log/)
-------------

http middleware 

```  
func [middlewareName](h http.Handler) http.Handler {
              return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
              // Do things before request 
           	
              nextMiddleware.ServeHTTP(w, r)
              // Do things after request	  
              })
          } 
```

{
         "http Middleware declaration": {
		"prefix": "md",
		"body": ["func $1(${2:nextMiddleware} http.Handler) http.Handler {\n\treturn http.HandlerFunc(func(${3:w} http.ResponseWriter, ${4:r} *http.Request) {\n\t $5\n\t nextMiddleware.ServeHTTP(${3:w}, ${4:r})\n\t 	  $6\n\t})\n}"],
		"description": "Snippet for http middleware declaration"
	},

	"log.Printf()": {
		"prefix": "lf",
		"body": [
			"log.Printf(\"\\n## ${1:text} ##: %+v\\n\", ${2:value})"
		],
		"description": "log.Printf()"
	},
	"fmt.Printf()": {
		"prefix": "ff",
		"body": [
			"fmt.Printf(\"\\n## ${1:text} ## :%+v \\n\", ${2:value})",
		],
		"description": "log.Printf()"
	}
}