Thread: vector of vectors

i'm trying to input data into a vector of vectors, but the program crashes.
there is no compile errors, but it is obvious that my logic is not valid.
it started to crash after i inserted the if statement.

Code:

#include <vector>
#include <iostream>
#include <fstream>
#include <conio.h>
#include <string>

using namespace std;

int main(int argc, char *argv[])
{ 
    vector< vector< unsigned long > > vecMemoryCache;

    long lgNumberOfBlocks=0;
    long lgBlocksPerSet=0;
    long lgByteAddress=0;
    long lgByteAddressConverted=0;
    long lgBlockSize=0;
    long lgAssociativity=0;
    long lgCacheSize=0;
    long lgHit=0;
    long lgMiss=0;
    unsigned long unlgTotalLoads=0;

    string stFileName(argv[2]);
    string stProgramName(argv[0]);

    if (argc != 9)
    {
        cout<<"!!Invalid Number of arguments.\nUsage: "<< argv[0] <<" -t <file_name> -s <cache_size> -b <block_size> -a <associativity>!!\n";
        exit(1);
    }

    ifstream inTraceFile(argv[2], ios::in);

    if(!inTraceFile.is_open())
    {
        cout<<"!!Unable to open file "<<argv[2]<<"!!\n";
        exit(2);
    }

    lgBlockSize = atoi(argv[6]);
    lgCacheSize = atoi(argv[4]);
    lgAssociativity = atoi(argv[8]);

    lgNumberOfBlocks = lgCacheSize/lgBlockSize;
    lgBlocksPerSet = lgNumberOfBlocks/lgAssociativity;
    
    /*
    Address Conversion
    Exact Details:
    Each line represents a byte adddress referenced by an executed load instruction. To help compress 
    the traces, instead of storing the absolute memory byte address, we store the difference from the 
    last address in the trace.
    
    I construct the Byte Address, Block  Address, and Cache Address.
    */

    if (lgAssociativity == 1)
    {
        while(inTraceFile>>lgByteAddress)
        {
            lgByteAddressConverted=lgByteAddressConverted+lgByteAddress;

            cout<<"Byte Address: "<<lgByteAddressConverted<<endl;
            cout<<"Block Address: "<<lgByteAddressConverted/lgBlockSize<<endl;
            cout<<"Cache Address: "<<(lgByteAddressConverted/lgBlockSize)%lgNumberOfBlocks<<endl;
            
            if(vecMemoryCache[0][(lgByteAddressConverted/lgBlockSize)%lgNumberOfBlocks]==lgByteAddressConverted/lgBlockSize)
            {
                lgHit++;
            }
            else
            {
                lgMiss++;
                vecMemoryCache[0][(lgByteAddressConverted/lgBlockSize)%lgNumberOfBlocks]=lgByteAddressConverted/lgBlockSize;
            }

            unlgTotalLoads++;

            if(getch()==113)
                break;
        }
    }

    cout<<"Program Name:    "<<stProgramName<<endl;
    cout<<"Trace File Name: "<<stFileName<<endl;
    cout<<"Cache Size:      "<<lgCacheSize<<endl;
    cout<<"Block Size:      "<<lgBlockSize<<endl;
    cout<<"Associativity:   "<<lgAssociativity <<endl;
    cout<<"Total Loads:     "<<unlgTotalLoads<<endl;
    cout<<"Total Hits:      "<<lgHit<<endl;
    cout<<"Total Misses:    "<<lgMiss<<endl;

    return 0;
}

If you haven't resized the vector, it will be empty, meaning that even [0] is out of bounds.

By the way, why do you first assume that there are at least 3 command line arguments, and only after you have used them check if the number is as expected.
In main() you might use return 1; etc instead of exit(1).

good point about testing the number of arguements.
I will make that revision.
So can I get an example of how you resize the vector?
I have never used one so far.
Can I resize it with a run time variable instead of a constant?

i need to insert items at specific index locations.
unfortunatly i'm unable to use it sequentially.
that would make it a lot easier.
i'm trying to simulate a direct mapped cache
so if i say for instance

Code:

vector< vector< unsigned long > vecAssociativity > vecMemoryCache;

vecAssociativity.resize(lgAssociativity);  
vecMemoryCache.resize(lgBlocksPerSet);

concidering the prior code, would this be valid?

Another question about a vector of vectors.
How would I erase a location in a vector?
Below is what I tried, but it doesn't work.
How would I do this?

Code:

for(int x =1;x< lgNumberOfBlocks; x++)
{
     if (vecLRU[1][x]==lgByteAddressConverted)
     {
           vecLRU[1][x].erase();
     }
}