money notation

.gitignore

@@ -0,0 +1,19 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories
+vendor/
+
+# Editor settings
+.vscode
+.idea

finance.go

@@ -0,0 +1,46 @@
+package humanize
+
+import (
+ "fmt"
+)
+
+func Finance(f float64) string {
+ switch n := f; {
+ case n >= 1_000_000_000_000_000:
+ s := fmt.Sprintf("%.f", f)
+ s = insertAt(1, '.', []rune(s[:4]))
+ return fmt.Sprintf("$%sQ", s)
+
+ case n >= 1_000_000_000_000:
+ s := fmt.Sprintf("%.f", f)
+ s = insertAt(1, '.', []rune(s[:4]))
+ return fmt.Sprintf("$%sT", s)
+
+ case n >= 1_000_000_000:
+ s := fmt.Sprintf("%.f", f)
+ s = insertAt(1, '.', []rune(s[:4]))
+ return fmt.Sprintf("$%sB", s)
+
+ case n >= 1_000_000:
+ s := fmt.Sprintf("%.f", f)
+ s = insertAt(1, '.', []rune(s[:4]))
+ return fmt.Sprintf("$%sM", s)
+
+ case n >= 1_000:
+ s := fmt.Sprintf("%.f", f)
+ s = insertAt(1, '.', []rune(s[:4]))
+ return fmt.Sprintf("$%sK", s)
+
+ case n < 1_000:
+ return fmt.Sprintf("$%.f", f)
+
+ default:
+ return "NaN"
+ }
+}
+
+func insertAt(index int, elem rune, slice []rune) string {
+ copy(slice[index+1:], slice[index:])
+ slice[index] = elem
+ return string(slice)
+}

finance_test.go

@@ -0,0 +1,30 @@
+package humanize
+
+import (
+ "math"
+ "testing"
+)
+
+func TestFinance(t *testing.T) {
+ tests := []struct {
+ name string
+ arg float64
+ want string
+ }{
+ {"Quadrillions", 2_475_260_494_216_000, "$2.47Q"},
+ {"Trillions", 2_475_260_494_216, "$2.47T"},
+ {"Billions", 2_475_260_494, "$2.47B"},
+ {"Millions", 2_475_260, "$2.47M"},
+ {"Thousands", 2_475, "$2.47K"},
+ {"Hundreds", 247, "$247"},
+ {"Tens", 24, "$24"},
+ {"NaN", math.NaN(), "NaN"},
+ }
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ if got := Finance(tt.arg); got != tt.want {
+ t.Errorf("Finance() = %v, want %v", got, tt.want)
+ }
+ })
+ }
+}