working on function parser

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "files.associations": {
+    "iosfwd": "cpp",
+    "string": "cpp",
+    "ostream": "cpp"
+  }
+}

main.cpp

@@ -1,30 +1,36 @@
 #include <iostream>
 #include <string>
+#include "parser.h"
 using namespace std;
 
-static class functions
+/*
+class functions
 {
   public:
     inline static const string functions1[1] = {"f(x)=ax+3"};
     inline static const string functions2[1] = {"f(x)=ax+bx-2"};
     inline static const int functions1size = 1;
     inline static const int functions2size = 1;
 };
+*/
+
+/*
+  Generating functions
+
+  int a = rand() % 10;
+
+
+*/
 
 void game_1() {
   cout << "Generating hidden constants..." << endl;
-  int func = rand() % functions::functions1size;
-  cout << "The function is: " << functions::functions1[func] << endl;
-  int constant = rand() % 10;
+  string func = "3*x+2";
+  cout << "The function is: " << func << endl;
+  int constant = 3;
 
   for (int i = 0; i < 10; i++) {
     int inputval = rand() % 10;
-    cout << "x = " << inputval << ": ";
-    switch (func) {
-      case 0:
-        cout << "f(x) = " << (constant * inputval + 3) << endl;
-        break;
-    }
+    cout << "x = " << inputval << ": " << Parser::parseFunction(func, inputval) << endl;
   }
 
   while (true) {

parser.cpp

@@ -0,0 +1,66 @@
+#include "parser.h"
+
+int ctoi(char a) {
+  char *c = &a;
+  int i = atoi(c);
+  return i;
+}
+
+string Parser::parseFunction(string functionin, int x) {
+  string function = functionin;
+  for (int i = 0; i < function.length(); i++) {
+    if (function[i] == '*') {
+      int mult1 = 0;
+      int mult2 = 0;
+      if (function[i - 1] == 'x') mult1 = x;
+      else mult1 = ctoi(function[i - 1]);
+      if (function[i + 1] == 'x') mult2 = x;
+      else mult2 = ctoi(function[i + 1]);
+      function[i] = to_string(mult1 * mult2)[0];
+      function[i + 1] = ' ';
+      function[i - 1] = ' ';
+      i--;
+    }
+    else if (function[i] == '/') {
+      int div1 = 0;
+      int div2 = 0;
+      if (function[i - 1] == 'x') div1 = x;
+      else div1 = ctoi(function[i - 1]);
+      if (function[i + 1] == 'x') div2 = x;
+      else div2 = ctoi(function[i + 1]);
+      function[i] = to_string(div1 / div2)[0];
+      function[i + 1] = ' ';
+      function[i - 1] = ' ';
+      i--;
+    }
+    remove_if(function.begin(), function.end(), isspace);
+  }
+  for (int i = 0; i < function.length(); i++) {
+    if (function[i] == '+') {
+      int add1 = 0;
+      int add2 = 0;
+      if (function[i - 1] == 'x') add1 = x;
+      else add1 = ctoi(function[i - 1]);
+      if (function[i + 1] == 'x') add2 = x;
+      else add2 = ctoi(function[i + 1]);
+      function[i] = to_string(add1 + add2)[0];
+      function[i + 1] = ' ';
+      function[i - 1] = ' ';
+      i--;
+    }
+    else if (function[i] == '-') {
+      int sub1 = 0;
+      int sub2 = 0;
+      if (function[i - 1] == 'x') sub1 = x;
+      else sub1 = ctoi(function[i - 1]);
+      if (function[i + 1] == 'x') sub2 = x;
+      else sub2 = ctoi(function[i + 1]);
+      function[i] = to_string(sub1 - sub2)[0];
+      function[i + 1] = ' ';
+      function[i - 1] = ' ';
+      i--;
+    }
+    remove_if(function.begin(), function.end(), isspace);
+  }
+  return function;
+}

parser.h

@@ -0,0 +1,8 @@
+#include <string>
+using namespace std;
+
+class Parser
+{
+  public:
+    static string parseFunction(string functionin, int x);
+};