1 files changed, 27 insertions, 0 deletions
diff --git a/src/strconv/ctoa.go b/src/strconv/ctoa.go
new file mode 100644
index 0000000..c16a2e5
--- /dev/null
+++ b/src/strconv/ctoa.go
@@ -0,0 +1,27 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv
+
+// FormatComplex converts the complex number c to a string of the
+// form (a+bi) where a and b are the real and imaginary parts,
+// formatted according to the format fmt and precision prec.
+//
+// The format fmt and precision prec have the same meaning as in FormatFloat.
+// It rounds the result assuming that the original was obtained from a complex
+// value of bitSize bits, which must be 64 for complex64 and 128 for complex128.
+func FormatComplex(c complex128, fmt byte, prec, bitSize int) string {
+	if bitSize != 64 && bitSize != 128 {
+		panic("invalid bitSize")
+	}
+	bitSize >>= 1 // complex64 uses float32 internally
+
+	// Check if imaginary part has a sign. If not, add one.
+	im := FormatFloat(imag(c), fmt, prec, bitSize)
+	if im[0] != '+' && im[0] != '-' {
+		im = "+" + im
+	}
+
+	return "(" + FormatFloat(real(c), fmt, prec, bitSize) + im + "i)"
+}