Added contents to do_while.cpp

Loops/do_while.cpp

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+#include <iostream>
+
+using namespace std;
+
+/*
+    Do while. A while loop with do.
+    It's literally this ^^^.
+*/
+
+void do_while_loop(int max) {
+    int x = 0; // define variable to increment and match condition
+    do { // commence the code block
+        cout << x << " "; // iterate over it and print with a space after the number
+        x++; // increment by + 1
+    } while (x < max); // while condition (same as while.cpp)
+}
+
+int main() {
+    do_while_loop(10); // calling function (you will know what max is by now I'm sure)
+    return 0;
+}