Gate compiler design notes for cse

Department of Computer Science & Engineering



COMPILER DESIGN

LAB MANUAL

, COMPILER DESIGN LAB SYLLABUS


Sl. No. List of Experiments Page No.

1 Design a lexical analyzer for given language and the lexical analyzer should ignore
redundant spaces, tabs and new lines. It should also ignore comments. Although the
1
syntax specification states that identifiers can be arbitrarily long, you may restrict the
length to some reasonable value. Simulate the same in C language.
2
Write a C program to identify whether a given line is a comment or not. 4

3
Write a C program to recognize strings under 'a', 'a*b+', 'abb'. 5

4
Write a C program to test whether a given identifier is valid or not. 8

5
Write a C program to simulate lexical analyzer for validating operators. 9

6 Write a C program for implementing the functionalities of predictive parser for the mini
11
language.
7 Write a C program for constructing of LL (1) parsing.
14

8 Write a C program for constructing recursive descent parsing.
21

9 Write a C program to implement LALR parsing.
29
10 a) Write a C program to implement operator precedence parsing.
b) Write a C program to implement Program semantic rules to calculate the 36
expression that takes an expression with digits, + and * and computes the value.
11 Convert the BNF rules into Yacc form and write code to generate abstract syntax tree
41
for the mini language specified in Note 1.
12 Write a C program to generate machine code from abstract syntax tree generated by the
parser. The instruction set specified in Note 2 may be considered as the target code.

, EXPERIMENT- 1

OBJECTIVE:
Design a lexical analyzer for given language and the lexical analyzer should ignore redundant spaces, tabs and
new lines. It should also ignore comments. Although the syntax specification states that identifiers can be
arbitrarily long, you may restrict the length to some reasonable value. Simulate the same in C language.
RESOURCE:
Turbo C ++
PROGRAM LOGIC:
1. Read the input Expression
2. Check whether input is alphabet or digits then store it as identifier
3. If the input is is operator store it as symbol
4. Check the input for keywords

PROCEDURE:
Go to debug -> run or press CTRL + F9 to run the program

PROGRAM:
#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||str
cmp("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';


1

, 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; }

2