getting started

include/calculate.h

@@ -0,0 +1,12 @@
+#ifndef CALCULATE_H_
+#define CALCULATE_H_
+
+int strlen(char* str);
+
+void strrev(char* str);
+
+int atoi(char* src, int target);
+
+float atof(char* src, float target);
+
+#endif