C program to implement C preprocessor

NOTE: You need to create two more files as well, in.c and out.c. The in.c file is used to give input and output is obtained at out.c. 

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <ctype.h

char id[10][10],val[10][10],c;

FILE *ifp,*ofp;

int defs=0,j;

int getword(char w[])

{

int l=0;

c=fgetc(ifp);

while(isalnum(c)||c==‘#’||(ispunct(c)==‘<’))

{

w[l++]=c;

c=fgetc(ifp);

}

w[l]=‘\0’;

return l;

}

int ismacro(char w[])

{

int i;

for(i=0;i<defs;i++)

if(strcmp(w,id[i])==0)

return i;

return -1;

}

main()

{

char word[20];

int i,l;

ifp=fopen(“in.c”,“r”);

ofp=fopen(“out.c”,“w”);

while(!feof(ifp))

{

if(strcmp(word,‘#define’)==0)

{

getword(word);

strcpy(id[defs],word);

getword(word);

strcpy(val[defs],word);

defs++;

}

}

printf(“\nDefinition\n”);

for(i=0;i<defs;i++)

printf(“%s\t%s\n”,id[i],val[i]);

rrewind(ifp);

while(!feof(ifp))

{

l=getword(word);

if(strcmp(word,“#define”)==0)

{

fprintf(ofp,“%s”,word);

printf(“%s”,word);

while((c=fgetc(idp))!=‘\n’)

{

fprintf(ofp,“%c”,c);

priintf(“%c”,c);

}

}

else if(l!=0)

if((j=ismacro(word))!=-1)

{

fprintf(ofp,“%s”,val[j]);

printf(“%s”,val[j]);

}

else

{

fprintf(ofp,“%s”,word);

printf(“%s”,word);

}

fprintf(ofp,“%c”,c);

printf(“%c”,c);

}

fclose(ifp);

fclose(ofp);

}