init taschenrechner and calendar

Taschenrechner/m_string.h

@@ -0,0 +1,39 @@
+#pragma once
+
+struct String {
+
+	size_t length;
+	char* data;
+
+	char operator[](int index) {
+		if (index < 0) {
+			return 0;
+		} 
+		if (index < length) {
+			return data[index];
+		}
+		return 0;
+	}
+};
+
+String operator""_str(const char* str, size_t length) {
+	return { length, (char*)str };
+}
+
+void advance(String &s, int num = 1) {
+	int to_advance = min(s.length, num);
+	s.data = s.data + to_advance;
+	s.length = s.length - to_advance;
+}
+
+bool starts_with(String s, String start) {
+	if (s.length < start.length) {
+		return false;
+	}
+	for (int i = 0; i < start.length; i++) {
+		if (s[i] != start[i]) {
+			return false;
+		}
+	}
+	return true;
+}