int main(int argc, char* argv[])
{
//input object
ifstream source;
//variables to store line, token, and
//boolean to determine end of line read
string myline;
string token = "";
bool done = false;
//Structure for symbol table
struct item
{
string tokenType;
string tokenName;
}table[1000];
//position in line read
int pos = 0;
int i = 0;
//Open source file
//source.open(argv[0]);
source.open("input.txt");
if(!source.is_open())
{
cout << "cant open file!";
return 0;
}
//Read til end of file
do
{
done = false;
//get line from input file
getline(source, myline);
if(!source.eof())
{
//do... while until line is read
do
{
char c = myline[pos++];
if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
{
token = token + c;
}
else if(c == '(' || c == ')' || c == '{' || c == '}' || c == ';'
|| c == '=' || c == '+' || c >= 0 || c <= 0)
{
if(token == "int" || token == "double" || token == "char")
{
table.tokenType = token;
i++;
}
cout << token << endl;
token = "";
cout << c << endl;
}
if (pos >= myline.length())
{
done = true;
pos = 0;
}
}while(!done);
}
}while(!source.eof());
//close input file
source.close();
//table format
cout << "Type Variable Name\n";
//loop to display each of the symbol tables data
for(int j = 0; j < i; j++)
{
cout << table[j].tokenType << " " << table[j].tokenName << endl;
}
system("pause");
return 0;
}
help with symbol table C++
Author
Here I have a simple parser program, and I am trying to add a symbol table to it so basically when it reads int, double or char it will store that as a tokenType and then I want it to read the name afterwords so say i then it will store that in tokenName. I have it storing the type, but I can't seem to wrap my head around having it read the next token without making it hardcoded to be a certain name like how I did int, double and char... any input would be very helpful, thank you.
Here is my code so far:
After you read the token type, assuming there's some sort of whitespace following, can't you just read in the remainder of the line (or until ';' or some other terminator is reached, etc.) and store whatever occurs?
FYI, if you have it, you may want to look at some of the "is" routines in the C run-time library: isalpha, isalnum, etc.
FYI, if you have it, you may want to look at some of the "is" routines in the C run-time library: isalpha, isalnum, etc.
Author
I thought that something like this would work, but nothing seems to be happening or at least that I see... anyone have any ideas here?
Here is my code so far:
Here is my code so far:
int main(int argc, char* argv[]){ //input object ifstream source; //variables to store line, token, and //boolean to determine end of line read string myline; string token = ""; string tName = ""; bool done = false; //Structure for symbol table struct item { string tokenType; string tokenName; }table[1000]; //position in line read int pos = 0; int i = 0; //Open source file //source.open(argv[0]); source.open("input.txt"); if(!source.is_open()) { cout << "cant open file!"; return 0; } //Read til end of file do { done = false; //get line from input file getline(source, myline); if(!source.eof()) { //do... while until line is read do { char c = myline[pos++]; if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) { token = token + c; } else if(c == '(' || c == ')' || c == '{' || c == '}' || c == ';' || c == '=' || c == '+' || c >= 0 || c <= 0) { if(token == "int" || token == "double" || token == "char") { table.tokenType = token; c = myline[pos++]; if(c == ' ') { if(c != ';') { c = myline[pos++]; tName = tName + c; } } table.tokenName = tName; i++; } cout << token << endl; token = ""; cout << c << endl; } if (pos >= myline.length()) { done = true; pos = 0; } }while(!done); } }while(!source.eof()); //close input file source.close(); //table format cout << "Type Variable Name\n"; //loop to display each of the symbol tables data for(int j = 0; j < i; j++) { cout << table[j].tokenType << " " << table[j].tokenName << endl; } system("pause"); return 0;}
What's up with:
That said, I might have misunderstood your intentions, but does this help:
else if(c == '(' || c == ')' || c == '{' || c == '}' || c == ';' || c == '=' || c == '+' || c >= 0 || c <= 0) if(c == ' ') { if(c != ';')That said, I might have misunderstood your intentions, but does this help:
#include <string>#include <iostream>#include <fstream>#include <algorithm>#include <vector>#include <iterator>#include <cctype>struct Item{ std::string tokenType, tokenName; Item(std::string tokenType, std::string tokenName) : tokenType(tokenType), tokenName(tokenName) {}};std::ostream& operator<<(std::ostream& os, const Item& item){ return os << item.tokenType << "\t" << item.tokenName;}typedef std::vector<Item> Table;bool DelimPred(char c){ return !std::isalpha(c);}int main(){ Table table; //Open source file std::ifstream source("input.txt"); if(!source) { std::cerr << "cant open file!" << std::endl; return 0; } //Read til end of file while(source.good()) { //get line from input file std::string line; std::getline(source, line); std::string::iterator it = std::find_if(line.begin(), line.end(), DelimPred); if(it == line.end()) { std::cerr << "Malformed line: " << line << std::endl; continue; } table.push_back(Item(std::string(line.begin(), it), std::string(it + 1, line.end()))); } //table format std::cout << "Type\tVariable Name" << std::endl; // display each of the symbol tables data std::copy(table.begin(), table.end(), std::ostream_iterator<Item>(std::cout, "\n"));}
Author
All those are the characters I want to read only. All of that reads fine the ' ' and ';' are ones I want to cancel the reading on the type and variable name. Basically what I want the symbol table to look like would be this, if I input a file that has
Aside from the parser it would output the following...
so far I got it doing all but the num part, any ideas on this?
main(){int num;return 0;}Aside from the parser it would output the following...
Type Variable Nameint numso far I got it doing all but the num part, any ideas on this?
Author
Okay I got it reading the variable name after the type and displaying it properly except for one minor problem it is adding the ; in there as well, I have to look at my confusing jumble of mess to see if I can find the problem, if you see it please feel free to point it out to me, thank you.
Here is my code now:
This is what my output looks like for the symbol table now,
**EDIT figured out that semi-colon problem so far it is running almost perfect, I need it to loop that process if a ',' is found.
Here is my code now:
int main(int argc, char* argv[]){ //input object ifstream source; //variables to store line, token, and //boolean to determine end of line read string myline; string token = ""; string tName = ""; bool done = false; //Structure for symbol table struct item { string tokenType; string tokenName; }table[1000]; //position in line read int pos = 0; int i = 0; //Open source file //source.open(argv[0]); source.open("input.txt"); if(!source.is_open()) { cout << "cant open file!"; return 0; } //Read til end of file do { done = false; //get line from input file getline(source, myline); if(!source.eof()) { //do... while until line is read do { char c = myline[pos++]; if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) { token = token + c; } else if(c == '(' || c == ')' || c == '{' || c == '}' || c == ';' || c == '=' || c == '+' || c >= 0 || c <= 0) { if(token == "int" || token == "double" || token == "char") { table.tokenType = token; while(c != ';') { c = myline[pos++]; tName = tName + c; } table.tokenName = tName; i++; } cout << token << endl; if(tName != "") { cout << tName << endl; } token = ""; tName = ""; cout << c << endl; } if (pos >= myline.length()) { done = true; pos = 0; } }while(!done); } }while(!source.eof()); //close input file source.close(); //table format cout << "Type Variable Name\n"; //loop to display each of the symbol tables data for(int j = 0; j < i; j++) { cout << table[j].tokenType << " " << table[j].tokenName << endl; } system("pause"); return 0;}This is what my output looks like for the symbol table now,
Type Variable Nameint num;**EDIT figured out that semi-colon problem so far it is running almost perfect, I need it to loop that process if a ',' is found.
You should really really tokenize your input _before_ you parse it. That'll simplify your code considerably. Your code as it is demonstrates a rather weird and incorrect idea of what a token is.
Quote:Original post by wicked357mattd's point was that your else condition is always true:
*** Source Snippet Removed ***
else if(c == '(' || c == ')' || c == '{' || c == '}' || c == ';' || c == '=' || c == '+' || c >= 0 || c <= 0)
Note the last two clauses - c must always be either <= or >= zero (because those two cases include all possible numbers). Thus, you can replace that massive else if(...) with a simple else statement.
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