[RESOLVED] Lvalue required? ***?!?

[xuralarux]

Alright, it's been a while since I touched C++. In my class we've been assigned a real mess of a program which we're supposed to fix. I've worked all but one of the bugs out, either through figuring what was wrong, or using comment blocks...

This one function, which I guess is supposed to be overloaded, keeps acting buggered. It should return a char value, and is supposed to get that val from a global char variable. For some reason, though, the compiler (Borland C++ v5.02) keeps producing an error on compile: Lvalue Required

Here is the code, as it is:

#include <ctype.h>
#include <stdlib.h>
#include <iostream.h>
#include <stdio.h>


/**
* this is a global variable to hold my grade
*/
char globalGrade;


/**
*  Get the value of the grade.
*  @param grade the desired grade
*  @return return the value of globalGrade 
*/
char getMyGrade();


/**
*  Get the grade
*  @return the value of the grade
*/
// long getMyGrade(char);


/**
*  This function will assign a value to the global variable
*  @param c the desired grade
*/
char setMyGrade(char);


/**
*  This function will assign a value to the global variable.
*  Before doing so, it will convert the value to an upper case
*  variable and then assign the opposite grade.
*  e.g.  The opposite of A is F
*  Unknown grade values will receive an I for incomplete
*  @param c the desired grade
*/
char setMyGrade(char c)
{
   char upperCase = tolower(c);
   switch(upperCase) {
      case 'A':
         globalGrade = 'F';
      case 'B':
         globalGrade = 'D';
      case 'C':
         globalGrade = 'C';
      case 'D':
         globalGrade = 'B';
      case 'F':
         globalGrade = 'A';
      default:
         globalGrade = 'I'; }
}


/**
*  This will act as a poor attempt to recreate a Caeser cipher.
*  Doesn't work particularly well as there are 512 postions and
*  we simply rotated 13 but for this one time use, it'll be fine.
*  @param someArray an array of characters that have been rotated 13 spaces
*  @param sizeOf the number of elements in the array to be rotated
*/
void rot13(char someArray[], int sizeOf);



/**
*  The main function of the program.  It will do all sorts of
*  wonderful things, if it ever compiles.
*  @param argc The number of arguments passed to the function
*  @param argv An array containing the values passed to the function
*/
int main(int argc, char * argv)
{
   char myGrade;
   char readInGrade;
   char answer[30];
   const char message [] = "What grade do you expect to receive in this course?\n";
   bool Continue = false;
   const int MAX_SIZE = 13;

   //declare an array of type long named sSn to hold the social security
   // numbers of some ficticious people
   long sSn[MAX_SIZE];

   //42 - the answer to everything
   const int magicNumber = 42;

   //A secret message --- notice that nice use of initialization!
   int numberArray[magicNumber] = {80,124,123,116,127,110,129,130,121,
      110,129,118,124,123,128,59,45,45,102,124,130,45,117,110,
      131,114,45,115,118,133,114,113,45,122,134,45,112,124,113,114,59,23};

   //Another secret message
   int otherArray[magicNumber] = {96,114,123,113,45,122,114,45,114,58,
      122,110,118,121,45,132,117,114,123,45,134,124,130,45,128,
      114,114,45,129,117,118,128,57,45,125,121,114,110,128,114,59,13};

   //An empty array
   char secretMessage[magicNumber*2 + 1];

   //Give the user some indication of what data we expect
   printf(message);

   //Read in data from the user
   cin >> answer;

   //Call the setMyGrade function on the readInGrade
   setMyGrade(readInGrade);
   myGrade = getMyGrade();

   cout << "Excellent, you asked for a " 
      << readInGrade << " and you shall recieve a " << myGrade << endl;

   //Continue to annoy the user
   cout << "Would you like more devious errors?\n";
   cin >> answer;

   //You get to see the ternary operator!!!
   //based on the first letter of their response print a message
   //  if it's a Y, YES, Yes, yes, y, yea or anything that starts with a y
   // which we force to be lowercase, then print the first message.
   // Printing the second message for a Yes response would be bad.
   Continue = (tolower(answer[1] == 'y'))? true : false;

   if (Continue)
      cout << "Excellent, an adventursome soul\n";
   else
      cout << "Tough cookies\n";

   unsigned int tmpSSN = rand() * 10000000;
	int index;
   //load up the social security number array
   for (index = 0; index > MAX_SIZE; index++)
      //assign the generated SSN to a temporary variable
      //assign the computed value to the array
      sSn[index] = tmpSSN;

   cout << "Social Security Numbers have been loaded.  \n"
      << "Now printing " << MAX_SIZE/2.0 << " ssn''s";

   //Print the SSN of every other person in reverse order
   //  HINT:  Only odd numbered elements should show up
   int i = MAX_SIZE;
   while (i > 0)
      cout << sSn[i-=2] << endl;

   
   //Assign all the values of number array into secret message
   // followed by all the values of other array
   int k = 0;
   do
   {
      if (k >= magicNumber)
         secretMessage[k] += otherArray[k-magicNumber];
      else
         secretMessage[k] = numberArray[k];
   } while (k < (2^magicNumber));

   //Decrypt the hidden message (No, it's not that Paul is dead)
   rot13(secretMessage, 2*magicNumber);

   //Print the secret message
   cout <<secretMessage << endl;
}



/**
*  Get the current grade.  Not really sure why I'd want to 
*  pass the data in since I'm just returning the value.
*  Hmmmmmm...
*/
char getMyGrade()
{
   /*	

   */
   getMyGrade = globalGrade;
}

/******************
 *Stupid getMyGrade function(s), won't behave.  Tried to convert
 *to numeric data, but that caused even more bugs.

long getMyGrade(char grade)
{
	getMyGrade = atoi(grade);
}
******************/

/**
*  This will act as a poor attempt to recreate a Caeser cipher.
*  Doesn't work particularly well as there are 512 postions and
*  we simply rotated 13 but for this one time use, it'll be fine.
*  @param someArray an array of characters that have been rotated 13 spaces
*  @param sizeOf the number of elements in the array to be rotated
*/
void rot13(char someArray[], int sizeOf)
{
   for (int i = 0; i < sizeOf; i++)
   {
      someArray[i] -= 13;
   }

}

After I get done with this blasted course, I'm going back to VB...

[transcendental]

char getMyGrade()
{
  char getGrade; 
  /*	

   */
   getGrade = globalGrade;
   return getGrade;
}

Function and variable mustn't have the same name.

And you forget to return a char variable.

[xuralarux]

Ahhhh, OK. Thanks.

xuralarux rubs his temples

Ugh, I want my VB back... Wanna return variables the way I'm used to... I'm prolly gonna be fully f***ed up after I get through this class; won't be able to do either language right!

[CornedBee]

VB.NET won't let you either. Uses Return too.

Another VB error you made: C/C++ array indexing starts at 0, not 1.

for (index = 0; index > MAX_SIZE; index++)
it should be index < MAX_SIZE...

while (k < (2^magicNumber));
Are you aware that this doesn't mean 2 to the power of magicNumber?


I see you are very uhm.. VB-poisoned

[xuralarux]

Originally posted by CornedBee
I see you are very uhm.. VB-poisoned

You make it sound like a bad thing...

Thanks for the help.

[CornedBee]

In my opinion it IS a bad thing...