Operator Precedence

Operator Precedence

   July 11, 2014       GRK

---

Simple program for operator precedence parser in C.
It takes the expression as input and calculates the precedence of the operators.

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PROGRAM CODE:

 #include<stdio.h>  
 #include<string.h>  
 void main()  
 {  
   int i,j,cnt=1;  
   char operators[] ="*/%+-",input[100];  
   printf("Enter the statement : ");  
   gets(input);  
   for(i=0;i<strlen(operators);i++)  
   {  
     for(j=0;j<strlen(input);j++)  
     {  
       if(input[j]==operators[i])  
       {  
         printf("%d %c=%c%c%c\n",cnt++,input[j-1],input[j-1],input[j],input[j+1]);  
         input[j+1]=input[j-1];  
       }  
     }  
   }  
 }  

OUTPUT:

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Notify the Suggestions about the program through comments ... :)

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Lexical Analyzer

Lexical Analyzer

   July 06, 2014       GRK

---

Simple Lexical Analyzer program. It takes the filename in the same directory as the input and analyzes the program for variables operators and special characters. and prints the output for each values separately.

 #include<stdio.h>  
 #include<conio.h>  
 #include<string.h>  
 void main()  
 {  
      FILE *fp;  
      int i=0;  
      char input[100],filename[20];  
      clrscr();  
      printf("Enter Filename : ");  
      scanf("%s",filename);  
      fp=fopen(filename,"r");  
      while(!feof(fp))  
      {  
           input[i]=fgetc(fp);  
           i++;  
      }  
      input[--i]='\0';  
      for(i=0;i<strlen(input);i++)  
      {  
           if(isalpha(input[i]))  
           {  
                printf("%c is a Character.\n",input[i]);  
           }  
           else if(input[i]=='='||input[i]=='+'||input[i]=='-'||input[i]=='*'||input[i]=='/'||input[i]=='%')  
           {  
                printf("%c is an Operator.\n",input[i]);  
           }  
           else if(isspace(input[i])||iscntrl(input[i]))  
           {  
           }  
           else if(isdigit(input[i]))  
           {  
                printf("%c is a number.\n",input[i]);  
           }  
           else  
           {  
                printf("%c is a Special character.\n",input[i]);  
           }  
      }  
      getch();  
 }  

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