Break down the statement into lexme's using regular expression then insert the tokens on the symbol table.

FlexTokenInsertionSymbolTable.l

%{

#include<bits/stdc++.h>
using namespace std;
#define CHAIN_LENGTH 53
#define M 128



struct symbol_info{
    char name[M];
    char classtype[M];
    struct symbol_info *next;
} *block[CHAIN_LENGTH];



int cHash(char* name){
    int idx = 0;
    for(int i = 0; name[i]; ++i){
        idx = idx + name[i];
    }
    return (idx % CHAIN_LENGTH);
}


void cInsert(char* name, char* classtype){
    int pos = cHash(name);

    if( block[pos] == NULL ){
        block[pos] = new symbol_info();
        strcpy(block[pos]->name, name);
        //block[pos]->name = name;
        strcpy(block[pos]->classtype, classtype);
        //block[pos]->classtype = classtype;
        block[pos]->next = NULL;
    }
    else{
        symbol_info* newNode = new symbol_info();
        strcpy(newNode->name, name);
        //newNode->name = name;
        strcpy(newNode->classtype, classtype);
        //newNode->classtype = classtype;

        // pointer swap
        symbol_info* nextNode = block[pos];
        block[pos] = newNode;
        newNode->next = nextNode;
    }
}


bool cSearch(char* name, char* classtype){
    // Implement
    int pos = cHash(name);

    symbol_info* temp = block[pos];

    while( temp != NULL ){
        if( !strcmp( temp->name, name ) && !strcmp( temp->classtype, classtype ) ){
            return true;
        }
        temp = temp->next;
    }

    return false;
}


void cDelete(char* name, char* classtype){
    int pos = cHash(name);

    symbol_info* temp = block[pos];
    if(temp == NULL) return;


    // At head but no one to follow
    if( temp->next == NULL && !strcmp( temp->name, name ) && !strcmp( temp->classtype, classtype ) ){
        block[pos] = NULL;
    }
    // At head has followers
    else if( !strcmp( temp->name, name ) && !strcmp( temp->classtype, classtype ) ){
        block[pos] = temp->next;
    }
    else{

        while( temp->next != NULL ){
                if ( !strcmp( temp->next->name, name ) && !strcmp( temp->next->classtype, classtype ) ){
                    printf("FOUND IT %s : %s\n", temp->name, temp->classtype );
                    break;
                }
            temp = temp->next;
        }



        if( temp != NULL ){
            symbol_info* found = temp->next;
            temp->next = found->next;
            delete(found);
        }


    }
}


void cUpdate(char* name, char* classtype, char* updatedClasstype){
    int pos = cHash(name);

    symbol_info* temp = block[pos];

    while( temp != NULL ){
        if( !strcmp( temp->name, name ) && !strcmp( temp->classtype, classtype ) ){
            strcpy(temp->classtype, updatedClasstype);
            //temp->classtype = updatedClasstype;

            return;
        }
        temp = temp->next;
    }
}


void showSymbolTable(){
    // Implement
    for(int i = 0; i < CHAIN_LENGTH; ++i){
        printf("%d:", i);

        // Do not modify the head
        symbol_info* temp = block[i];

        while( temp != NULL ){
            printf("->[%s|%s]", temp->name, temp->classtype);
            temp = temp->next;
        }

        printf("\n");
    }
}


int showMenu(){
    cout << "Menu:\n";
    cout << "=====\n";

    string message = "Enter 1 to insert(name, class type)\n"
                     "Enter 2 to update(name, class type, new class type)\n"
                     "Enter 3 to search(name, class type)\n"
                     "Enter 4 to delete(name, class type)\n"
                     "Enter 5 to show the symbol table\n";

    cout << message << "\n";


    cout << "User Choice: ";
    int choice;
    scanf("%d", &choice);


    return choice;
}


int line_count = 0;


%}

printsymboltable "pst"
group1	"]"|"["|"("|")"|","|";"|":"
addgroup "+"|"-"|"or"
mulgroup "*"|"/"|"mod"|"and"|"div"
relgroup "="|"<>"|">="|"<"|">"|"<="
keywordgroup "program"|"if"|"not"|"end"|"begin"|"else"|"then"|"do"|"while"|"function"|"Procedure"|"integer"|"real"|"var"|"oh"|"array"|"write"
pascalcomment ^\{.*\}$
numbersgroup ([0-9]*)|([+-]?([1-9][0-9]*[.][0-9]+)([E][-+][1-9][0-9]*)?)
variablegroup [a-zA-Z_][A-Za-z0-9_]*
singlelinecomments (\/\*.*\*\/)|(\/\/.*)
doublequotedstrings \".*\"

%%

[/][*][^*]*[*]+([^*/][^*]*[*]+)*[/] {
	printf("MULTILINE COMMENT:\n%s\n", yytext);
}


[\n] {
	++line_count;
	printf("\nLine Count:%d\n", line_count);
}



{keywordgroup} {
	string s(yytext);
	transform(s.begin(), s.end(), s.begin(), ::toupper);
	cout << "Keyword:" << s << "\n";
}


{printsymboltable} {
	showSymbolTable();
}

{group1} {
	printf("Symbols:%s\n", yytext);
}

{addgroup} {
	// Remove the warnings about deprecated strings conversion
	char classtype_attribute[] = "ADDOP";
	cInsert(yytext, classtype_attribute);
	printf("ADDOP:%s\n", yytext);
}

{mulgroup} {
	char classtype_attribute[] = "MULOP";
	cInsert(yytext, classtype_attribute);
	printf("MULOP:%s\n", yytext);
}

{relgroup} {
	char classtype_attribute[] = "RELOP";
	cInsert(yytext, classtype_attribute);
	printf("RELOP:%s\n", yytext);
}

".." {
	char classtype_attribute[] = "DOTDOT";
	cInsert(yytext, classtype_attribute);
	printf("DOTDOT:%s\n", yytext);
}

":=" {
	char classtype_attribute[] = "ASSIGNOP";
	cInsert(yytext, classtype_attribute);
	printf("ASSIGNOP:%s\n", yytext);
}

{pascalcomment} {
	printf("Pascal Comment:%s\n", yytext);
}

{numbersgroup} {
	char classtype_attribute[] = "Number";
	cInsert(yytext, classtype_attribute);
	printf("Number:%s\n", yytext);
}


{variablegroup} {
	char classtype_attribute[] = "Indentifier";
	cInsert(yytext, classtype_attribute);
	printf("Variable:%s\n", yytext);
}

{singlelinecomments} {
	printf("Comment:%s\n", yytext);
}

{doublequotedstrings} {
	printf("String: %s\n", yytext);
}


%%
int main(){
	yylex();	
	return 0;
}