Use the logic in that program to design your own Recursive Descent parser in Cfor the following grammar:S →aABA →Abc | bB →d Make sure that you choose at least two strings that pass the grammar and onestring that does not pass the grammar just like I did in the model program. /* Recursive Descent Parser for the Expression Grammar:S → (L) |aL' →,SL'|εL → SL'Valid inputs: (a,(a,a)) and (a,(a,(a,a),(a,a)))Invalid inputs:(aa,a)*/ #include <stdio.h>#include <string.h>int S(), Ldash(), L();char *ip;char string[50]; int main() { printf("Enter the string\n"); scanf("%s",string); ip = string; printf("\n\nInput\t\tAction\n ------------------------------\n"); if (S()) { printf("\n------------------------------\n"); printf("\n String is successfully parsed\n"); } else { printf("\n------------------------------\n"); printf("Error in parsing string\n"); }} int L(){ printf("%s\t\tL -> SL'\n", ip); if (S()) { if (Ldash()) { return 1; } else return 0; } else return 0;} int Ldash(){ if (*ip == ',') { printf("%s\t\tL' -> ,SL'\n", ip); ip++; if (S()) { if (Ldash()) { return 1; } else return 0; } else return 0; } else { printf("%s\t\tL' -> ε\n", ip); return 1; }} int S(){ if (*ip == '(') { printf("%s\t\tS →(L) \n", ip); ip++; if (L()) { if (*ip == ')') { ip++; return 1; } else return 0; } else return 0; } else if (*ip == 'a') { ip++; printf("%s\t\tS →a \n", ip); return 1; }else return 0;}
Use the logic in that program to design your own Recursive Descent parser in C
for the following grammar:
S →aAB
A →Abc | b
B →d
Make sure that you choose at least two strings that pass the grammar and one
string that does not pass the grammar just like I did in the model program.
/* Recursive Descent Parser for the Expression Grammar:
S → (L) |a
L' →,SL'|ε
L → SL'
Valid inputs: (a,(a,a)) and (a,(a,(a,a),(a,a)))
Invalid inputs:(aa,a)
*/
#include <stdio.h>
#include <string.h>
int S(), Ldash(), L();
char *ip;
char string[50];
int main()
{
printf("Enter the string\n");
scanf("%s",string);
ip = string;
printf("\n\nInput\t\tAction\n ------------------------------\n");
if (S())
{
printf("\n------------------------------\n");
printf("\n String is successfully parsed\n");
}
else
{
printf("\n------------------------------\n");
printf("Error in parsing string\n");
}
}
int L()
{
printf("%s\t\tL -> SL'\n", ip);
if (S())
{
if (Ldash())
{
return 1;
}
else
return 0;
}
else
return 0;
}
int Ldash()
{
if (*ip == ',')
{
printf("%s\t\tL' -> ,SL'\n", ip);
ip++;
if (S())
{
if (Ldash())
{
return 1;
}
else
return 0;
}
else
return 0;
}
else
{
printf("%s\t\tL' -> ε\n", ip);
return 1;
}
}
int S()
{
if (*ip == '(')
{
printf("%s\t\tS →(L) \n", ip);
ip++;
if (L())
{
if (*ip == ')')
{
ip++;
return 1;
}
else
return 0;
}
else
return 0;
}
else if (*ip == 'a')
{
ip++;
printf("%s\t\tS →a \n", ip);
return 1;
}
else
return 0;
}
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