added tutorial 15 cpp file from local machine

Author: SevenLinesOfCode

tut15.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+using namespace std;
+
+// Function prototype
+// syntax ---> function-name (arguments);
+// gives assurity that required function is present int the code
+
+// int sum(int a, int b); // -- Acceptable
+// int sum(int a, b); // -- Not Acceptable
+int sum(int, int); // -- Acceptable
+
+// void g(void); acceptable//
+void g ();
+
+int main () {
+    int num1, num2;
+
+    printf("Enter first number: ");
+    scanf("%d", &num1);
+
+    printf("\n");
+
+    printf("Enter second number: ");
+    scanf("%d", &num2);
+
+    printf("\n");
+
+    // num1, num2 are actual parameters
+    printf("The sum is: ");
+    printf("%d", sum(num1, num2));
+
+    g();
+
+    return 0;
+}
+
+// defining a function
+int sum(int a, int b) {
+    // Formal Paramertes, a and b will be taking values 
+    // from actual parameters num1 and num2
+    int c = a+b;
+    return c;
+}
+
+// void functions 
+void g() {
+    printf("This is a greeting messge!");
+}