C++ decleration of a two pass Assembler

#include<stdio.h>
#include<string.h>
#include<conio.h>
void chk_label();
void chk_opcode();
void READ_LINE();
struct optab
{
char code[10],objcode[10];
}myoptab[3]={
{ "LDA" , "00" },
{ "JMP" , "01" },
{ "STA" , "02" }
};
struct symtab{
char symbol[10];
int addr;
}mysymtab[10];
int startaddr,locctr,symcount=0,length;
char line[20],label[8],opcode[8],operand
[8],programname[10];
/*ASSEMBLER PASS 1 */
void PASS1()
{
FILE
*input,*inter;
input= fopen
( "input.txt" , "r" );
inter= fopen ( "inter.txt" , "w" );
printf( "LOCATION LABEL\tOPERAND\tOPCODE
\n" );
printf
( "_____________________________________" );
fgets(line,20,input);
READ_LINE();
if (! strcmp(opcode, "START" ))
{
startaddr= atoi (operand);
locctr=startaddr;
strcpy(programname,label);
fprintf(inter, "%s" ,line);
fgets (line,20,input);
}
else
{
programname[0]= '\0' ;
startaddr=0;
locctr=0;
}
printf ( "\n %d\t %s\t%s\t
%s" ,locctr,label,opcode,operand);
while ( strcmp(line, "END" )!=0)
{
READ_LINE();
printf( "\n %d\t %s \t%s\t
%s" ,locctr,label,opcode,operand);
if (label[0]!= '\0' )chk_label
();
chk_opcode();
fprintf(inter, "%s %s %s
\n" ,label,opcode,operand);
fgets (line,20,input);
}
printf( "\n %d\t\t
%s" ,locctr,line);
fprintf(inter, "%s" ,line);
fclose (inter);
fclose (input);
}
/*Assesmbler pass 2 */
void PASS2()
{
FILE *inter,*output;
char record[30],part[8],value[5]; /*Part
array was defined as part[6] previously*/
int
currtxtlen=0,foundopcode,foundoperand,chk,operandaddr,recaddr=0;
inter= fopen ( "inter.txt" , "r" );
output= fopen( "output.txt" , "w" );
fgets(line,20,inter);
READ_LINE();
if (! strcmp(opcode, "START" )) fgets
(line,20,inter);
printf( "\n\nCorresponding Object code
is..\n" );
printf( "\nH^ %s ^ %d ^ %d
" ,programname,startaddr,length);
fprintf(output, "\nH^ %s ^ %d ^ %d
" ,programname,startaddr,length);
recaddr=startaddr; record[0]= '\0' ;
while( strcmp(line, "END" )!=0)
{
operandaddr=foundoperand=foundopcode=0;
value[0]=part[0]= '\0' ;
READ_LINE();
for (chk=0;chk<3;chk++)
{
if (! strcmp (opcode,myoptab
[chk].code))
{
foundopcode=1;
strcpy(part,myoptab
[chk].objcode);
if (operand[0]!= '\0' )
{
for (chk=0;chk<symcount;chk++)
if (! strcmp(mysymtab
[chk].symbol,operand))
{
itoa(mysymtab
[chk].addr,value,10);
strcat(part,value);
foundoperand=1;
}
if (!foundoperand) strcat
(part, "err" );
}
}
}
if (!foundopcode)
{
if ( strcmp(opcode, "BYTE" )==0 ||
strcmp(opcode, "WORD" )|| strcmp
(opcode, "RESB" ))
{
strcat(part,operand);
}
}
if ((currtxtlen+ strlen (part))<=8)
/*This step was having buffer overflow issue
since part[6]
was defined previously which i corrected to
part[8].
Because of this first two bytes of stack are
getting lost*/
{
strcat(record, "^" );
strcat(record,part);
currtxtlen+= strlen(part);
}
else
{
printf ( "\nT^ %d ^%d
%s" ,recaddr,currtxtlen,record);
fprintf(output, "\nT^ %d ^%d
%s" ,recaddr,currtxtlen,record);
recaddr+=currtxtlen;
currtxtlen= strlen (part);
strcpy (record,part);
}
fgets (line,20,inter);
}
printf( "\nT^ %d ^%d
%s" ,recaddr,currtxtlen,record);
fprintf(output, "\nT^ %d ^%d
%s" ,recaddr,currtxtlen,record);
printf( "\nE^ %d\n" ,startaddr);
fprintf(output, "\nE^ %d\n" ,startaddr);
fclose(inter);
fclose(output);
}
void READ_LINE()
{
char buff[8],word1[8],word2[8],word3[8];
int i,j=0,count=0;
label[0]=opcode[0]=operand
[0]=word1[0]=word2[0]=word3[0]= '\0' ;
for (i=0;line[i]!= '\0' ;i++)
{
if (line[i]!= ' ' )
buff[j++]=line[i];
else
{
buff[j]= '\0' ;
strcpy(word3,word2);
strcpy(word2,word1);
strcpy(word1,buff);
j=0;
count++;
}
}
buff[j-1]= '\0' ;
strcpy(word3,word2);
strcpy(word2,word1);
strcpy(word1,buff);
switch(count)
{
case 0: strcpy (opcode,word1);
break ;
case 1:{ strcpy (opcode,word2); strcpy
(operand,word1);}
break ;
case 2:{ strcpy (label,word3); strcpy
(opcode,word2); strcpy(operand,word1);}
break ;
}
}
void chk_label()
{
int k,dupsym=0;
for (k=0;k<symcount;k++)
if (! strcmp(label,mysymtab[k].symbol))
{
mysymtab[k].addr=-1;
dupsym=1;
break ;
}
if (!dupsym)
{
strcpy (mysymtab
[symcount].symbol,label);
mysymtab[symcount++].addr=locctr;
}
}
void chk_opcode()
{
int k=0,found=0;
for (k=0;k<3;k++)
if (! strcmp(opcode,myoptab[k].code))
{
locctr+=3;
found=1;
break ;
}
if (!found)
{
if (! strcmp( opcode, "WORD" )) locctr
+=3;
else if (! strcmp
(opcode, "RESW" ))locctr+=(3* atoi (operand));
else if (! strcmp
(opcode, "RESB" ))locctr+= atoi (operand);
}
}
int main()
{
PASS1();
length=locctr-startaddr;
PASS2();
getch();
}