Compiler Design (Exp 1)

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Compiler Design (Exp 1)

Task - 

To print the count of the number of keywords, identifiers, operators, and symbols after reading a line of code as input, then store each of these in an array and display them as an output.

Logic - 

  1. Accept STRING input using getline().
  2. Make a function 'to_vector()' to store each element of the input as a vector element.
  3. Call each function keyword(), identifier(), operator() and symbols().
  4. Traverse the vector elements for each function call and see if there is a particular match.
  5. Increase the count and display as required.
  6. Declare global vector variables to store these details separately.

#include<bits/stdc++.h>
using namespace std;

vector<string> keys;
vector<string> oper;
vector<string> ident;
vector<string> syms;

vector<string> to_vector(string input)
{
    vector<string> temp;
    int k=0;
    for(int i=0;i<input.length();i++)
    {
        string part="";
        if(input[i]==' ')
        {
            for(int j=k;j<i;j++)
            {
                part+=input[j];
            }
            k=i+1;
            temp.push_back(part);
        }
    }
    return temp;
}

int keyword_count(vector<string> parts)
{
    int count=0;
    for(int i=0;i<parts.size();i++)
    {
        if(parts[i]=="int"||parts[i]=="float"||parts[i]=="while"||parts[i]=="for")
        {
            count++;
            keys.push_back(parts[i]);  
        }
    }
    return count;
}

int identifier_count(vector<string> parts)
{
    int count=0;
    for(int i=0;i<parts.size();i++)
    {
        if(parts[i]=="a"||parts[i]=="b"||parts[i]=="c"||parts[i]=="i"||parts[i]=="j")
        {
            count++;
            ident.push_back(parts[i]);
        }
    }
    return count;
}

int operator_count(vector<string> parts)
{
    int count=0;
    for(int i=0;i<parts.size();i++)
    {
        if(parts[i]=="+"||parts[i]=="++"||parts[i]=="-"||parts[i]=="--"||parts[i]=="=")
        {
            count++;
            oper.push_back(parts[i]);
        }
    }
    return count;
}

int seperator_count(vector<string> parts)
{
    int count=0;
    for(int i=0;i<parts.size();i++)
    {
        if(parts[i]==";"||parts[i]=="//")
        {
            count++;
            syms.push_back(parts[i]);
        }
    }
    return count;
}

int main()
{
    string input;
   
    cout<<"How to give input!"<<endl;
    cout<<"1. Give proper space for each & every synatx"<<endl;
    cout<<"2. After the input hit 'spacebar' and add a '/' symbol."<<endl;
    cout<<"Example -> int a = b + c ; /"<<endl;
    cout<<"Or -> for ( int i = 0 ; i < n ; i ++ ) /"<<endl;
    cout<<endl<<"Enter proper input (or may not yield proper result) - "<<endl;
   
    getline(cin,input);
   
    cout<<endl;
   
    vector<string> parts;
    parts = to_vector(input);
   
    int key,op,sep,id;
   
    key = keyword_count(parts);
    op = operator_count(parts);
    sep = seperator_count(parts);
    id = identifier_count(parts);
   
    cout<<key<<" keywords"<<endl;
    cout<<op<<" operators"<<endl;
    cout<<sep<<" seperators"<<endl;
    cout<<id<<" identifiers"<<endl;
   
    cout<<endl<<"The keywords are -> ";
    for(int i=0;i<keys.size();i++)
    {
        cout<<keys[i]<<" ";
    }
    cout<<endl<<"The operators are -> ";
    for(int i=0;i<oper.size();i++)
    {
        cout<<oper[i]<<" ";
    }
    cout<<endl<<"The seperators are -> ";
    for(int i=0;i<syms.size();i++)
    {
        cout<<syms[i]<<" ";
    }
    cout<<endl<<"The identifiers are -> ";
    for(int i=0;i<ident.size();i++)
    {
        cout<<ident[i]<<" ";
    }
}

Output & Result - 


The first phase ( Lexical analysis ) is implemented using C++ for compiler design.

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