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rec.c
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rec.c
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#include <stdio.h>
#include <string.h>
char input[100];
int i, l;
void main()
{
printf("\nRecursive descent parsing for the following grammar\n");
printf("\nE->TE'\nE'->+TE'/@\nT->FT'\nT'->*FT'/@\nF->(E)/ID\n");
printf("\nEnter the string to be checked:");
gets(input);
if (E())
if (input[i + 1] == '\0')
printf("\nString is accepted");
else
printf("\nString is not accepted");
else
printf("\nString not accepted");
}
int E()
{
if (T())
{
if (EP())
return (1);
else
return (0);
}
else
return (0);
}
int EP()
{
if (input[i] == '+')
{
i++;
if (T())
{
if (EP())
return (1);
else
return (0);
}
else
return (0);
}
else
return (1);
}
int T()
{
if (F())
{
if (TP())
return (1);
else
return (0);
}
else
return (0);
}
int TP()
{
if (input[i] == '*')
{
i++;
if (F())
{
if (TP())
return (1);
else
return (0);
}
else
return (0);
}
else
return (1);
}
int F()
{
if (input[i] == '(')
{
i++;
if (E())
{
if (input[i] == ')')
{
i++;
return (1);
}
else
return (0);
}
else
return (0);
}
else if (input[i] >= 'a' && input[i] <= 'z' || input[i] >= 'A' && input[i] <= 'Z')
{
i++;
return (1);
}
else
return (0);
}