#include<string.h>
#include<ctype.h>
#include<stdio.h>
void keyword(char str[10])
{
    if(strcmp("for",str)==0||strcmp("while",str)==0||strcmp("do",str)==0||strcmp("int",str )==0||strcmp("float",str)==0||strcmp("char",str)==0||strcmp("double",str)==0||strcmp("static",str)==0||strcmp("switch",str)==0||strcmp("case",str)==0)
        printf("\n%s is a keyword",str);
    else
        printf("\n%s is an identifier",str);
}
main()
{
    FILE *f1,*f2,*f3;
    char c,str[10],st1[10];
    int num[100],lineno=0,tokenvalue=0,i=0,j=0,k=0;
    printf("\nEnter the c Program: ");/*gets(st1);*/
    f1=fopen("input","w");
    while((c=getchar())!=EOF)
        putc(c,f1);
    fclose(f1);
    f1=fopen("input","r");
    f2=fopen("identifier","w");
    f3=fopen("specialchar","w");
    while((c=getc(f1))!=EOF)
    {
        if(isdigit(c))
        {
            tokenvalue=c-'0';
            c=getc(f1);
            while(isdigit(c))
            {
                tokenvalue*=10+c-'0';
                c=getc(f1);
            }
            num[i++]=tokenvalue;
            ungetc(c,f1);
        }
        else if(isalpha(c))
        {
            putc(c,f2);
            c=getc(f1);
            while(isdigit(c)||isalpha(c)||c=='_'||c=='$')
            {
                putc(c,f2);
                c=getc(f1);
            }
            putc(' ',f2);
            ungetc(c,f1);
        }
        else if(c==' '||c=='\t')
            printf(" ");
        else if(c=='\n')
            lineno++;
        else
            putc(c,f3);
    }
    fclose(f2);
    fclose(f3);
    fclose(f1);
    printf("\nThe no's in the program are");
    for(j=0; j<i; j++)
        printf("%d",num[j]);
    printf("\n");
    f2=fopen("identifier","r");
    k=0;
    printf("The keywords and identifiersare:");
    while((c=getc(f2))!=EOF)
    {
        if(c!=' ')
            str[k++]=c;
        else
        {
            str[k]='\0';
            keyword(str);
            k=0;
        }
    }
    fclose(f2);
    f3=fopen("specialchar","r");
    printf("\nSpecial characters are");
    while((c=getc(f3))!=EOF)
        printf("%c",c);
    printf("\n");
    fclose(f3);
    printf("Total no. of lines are:%d",lineno);
}

SAMPLE OUTPUT:

Enter the c Program: a+b*c
^Z
 
The no's in the program are
The keywords and identifiersare:
a is an identifier
b is an identifier
c is an identifier
Special characters are+*
Total no. of lines are:1