Write a program to implement Lexical Analyzer. System Programming GTU 2150708

Program:-

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<ctype.h>

int isKeyword(char buffer[]){

    char keywords[32][10] = {"auto","break","case","char","const","continue","default",

                            "do","double","else","enum","extern","float","for","goto",

                            "if","int","long","register","return","short","signed",

                            "sizeof","static","struct","switch","typedef","union",

                            "unsigned","void","volatile","while"};

    int i, flag = 0;

   

    for(i = 0; i < 32; ++i){

        if(strcmp(keywords[i], buffer) == 0){

            flag = 1;

            break;

        }

    }

   

    return flag;

}

int main(){

    char ch, buffer[15], operators[] = "+-*/%=";

    FILE *fp;

    int i,j=0;

   

    fp = fopen("abc.txt","r");

   

    if(fp == NULL){

        printf("error while opening the file\n");

        exit(0);

    }

   

    while((ch = fgetc(fp)) != EOF){

           for(i = 0; i < 6; ++i){

               if(ch == operators[i])

                   printf("%c is operator\n", ch);

           }

          

           if(isalnum(ch)){

               buffer[j++] = ch;

           }

           else if((ch == ' ' || ch == '\n') && (j != 0)){

                   buffer[j] = '\0';

                   j = 0;

                                     

                   if(isKeyword(buffer) == 1)

                       printf("%s is keyword\n", buffer);

                   else

                       printf("%s is indentifier\n", buffer);

           }

          

    }

   

    fclose(fp);

   

    return 0;

}

Output:-

[root@SAR126 Desktop]# gedit lexicalanay.c

[root@SAR126 Desktop]# gcc lexicalanay.c

[root@SAR126 Desktop]# ./a.out

+ is operator

= is operator

abc is indentifier

[root@SAR117 Desktop]# cat abc.txt

a+b=c