Trying to do this homework assignment but I keep getting a compilation error

This is only the first part of my homework, I've fixed all the other compilation errors but I keep getting this error, theres five. ``` 1>\takehome\main.cpp(39) : error C2065: 'j' : undeclared identifier 1>\takehome\main.cpp(44) : error C2065: 'j' : undeclared identifier \takehome\main.cpp(45) : error C2065: 'j' : undeclared identifier \takehome\main.cpp(76) : error C2065: 'j' : undeclared identifier \takehome\main.cpp(80) : error C2065: 'j' : undeclared identifier ``` I've tried doing everything with it, but I'm probably doing something wrong..obviously I am. I could use some help if you don't mind :). Btw, in case anyone was wondering, doing simpletron. ``` #include <iostream> using namespace std; int main() { int memory[100]; //Making it 100, since simpletron contains a 100 word mem. int operation; //taking the rest of these variables straight out of the book seeing as how they were italisized. int operand; int accum = 0; // the special register is starting at 0 int position = 0; //making the starting position to be 0. for ( int j = 0; j < 100; j++ ) //Simply stating that for int j is = to 0, j must be less than 100 because that is the memory limit, and for every pass-through, increment j. memory[j] = 0; // This is for part a, it will take in positive variables in a sent-controlled loop and compute + print their sum. These are random variables. memory [0] = 2942; memory [1] = 2342; memory [2] = 3523; memory [3] = 2031; memory [4] = 5000; memory [5] = 8080; memory [6] = 3425; j = 0; //Makes the variable j start at 0. while ( true ) { memory[ j ]%100 = operand; // Finds the op codes from the limit on the memory (100) memory[ j ]%100 = operation; //using a switch loop to set up the loops for the cases switch ( operation ){ case 1: //reads a variable into a word from loc. cout <<"\n Input a positive variable: "; cin >> memory[ operand ]; break; case 2: // takes a word from location cout << "\n\nThe content at location " << operand << "is " << memory[operand]; break; case 3:// loads accum = memory[ operand ]; break; case 4: //stores memory[ operand ] = accum; break; case 5: //adds accum = accum + memory[ operand ]; break; case 6: // subtracts accum = accum - memory[ operand ]; break; case 7: //divides accum = accum / (memory[ operand ]); break; case 8: // multiplies accum = accum*memory [ operand ]; break; case 9: // Branches to location j = -1; break; case 10: //branches if acc. is < 0 if (accum < 0) j = 5; break; case 11: //branches if acc = 0 if (accum == 0); break; case 12: // Program ends exit(0); break; } j++; } return 0; } ```