Question

I’m reading in from a text file that contains some assembly instructions that look like this

[label] opcode [arg1] [,arg2]

Right now I’m only at the stage of reading in the label but when I read from the file and input the labels into an array, I’m getting some blank lines that shouldn’t be there. Here is my code

#include <string>
#include <iostream>
#include <cstdlib>
#include <string.h>
#include <fstream>
#include <stdio.h>



using namespace std;


int main(int argc, char *argv[])
{
// If no extra file is provided then exit the program with error message
if (argc <= 1)
{
    cout << "Correct Usage: " << argv[0] << " <Filename>" << endl;
    exit (1);
}

// Array to hold the registers and initialize them all to zero
int registers [] = {0,0,0,0,0,0,0,0};

string memory [16000];

string Symtablelab[1000];
int Symtablepos[1000];


string line;
string label;
string opcode;
string arg1;
string arg2;


// Open the file that was input on the command line
ifstream myFile;
myFile.open(argv[1]);


if (!myFile.is_open())
{
    cerr << "Cannot open the file." << endl;
}

int counter = 0;
int i = 0;
int j = 0;

while (getline(myFile, line, '\n'))
{

    if (line[0] == '#')
    {
        continue;
    }


    if (line[0] != '\t' && line[0] != ' ')
    {

        string delimeters = "\t";

        int current;
        int next = -1;


        current = next + 1;
        next = line.find_first_of( delimeters, current);
        label = line.substr( current, next - current );

        Symtablelab[i] = label;

        cout << Symtablelab[i] << endl;

        i++;

    }


}


return 0;
}

The output I get from this code is:

blank line
TOP
VAL
TAN
blank line

I should only be getting:

TOP
VAL
TAN

Here is the sample text file I’m reading from

# Sample Input

    LA 1,3
    LA 2,1
TOP     NOP
    ADDR 3,1
    ST 3, VAL
    CMPR 3,4
    JNE TOP
    P_INT 1,VAL
    P_REGS
    HALT
VAL     INT 0
TAN     LA  2,1

Answer 1

The blank line after the comment and the implicit blank line at end are causing your problems. You should add a check after the comment check for blank lines.

if (line.length == 0) {
  continue;
}