test: find_minmax

histogram.cpp

@@ -1,6 +1,6 @@
 #include "histogram.h"
 using namespace std;
-static void find_minmax(const vector<double>& numbers, double& min, double& max)
+void find_minmax(const vector<double>& numbers, double& min, double& max)
 {
     min = numbers[0];
     max = numbers[0];

histogram_internal.h

@@ -0,0 +1,9 @@
+#ifndef HISTOGRAM_INTERNAL_H_INCLUDED
+#define HISTOGRAM_INTERNAL_H_INCLUDED
+
+#include <vector>
+
+void
+find_minmax(const std::vector<double>& numbers, double& min, double& max)
+
+#endif // HISTOGRAM_INTERNAL_H_INCLUDED

text.h

@@ -1,6 +1,6 @@
 #ifndef TEXT_H_INCLUDED
 #define TEXT_H_INCLUDED
-
+#include <vector>
 void
 show_histogram_text(const std::vector<size_t>& bins, size_t& bin_count);