Lexical analyzer using c programming language

lexical_analyzer.c

#include <stdio.h>
#include <string.h>

void lexicalAnalyzer(char S[]);
int isIdent(char ch);
int isAlpha(char ch);
int isDigit(char ch);
int isOperator(char ch);
int isDel(char ch);
void isKeyword();

char A[100], ident[50][30], oper[50][5], delim[50][5], keyword[180][20];
int i=0, j=0, c=0, k=0, idi=0, idj=0, opi=0, opj=0, deli=0, delj=0;
char op[8] = {'+', '-', '*', '/', '=', '&', '|', '!'};
char del[8] = {'(', ')', '{', '}', '[', ']', '"', ';'};
char kword[32][30] = {
    "auto",
    "double",
    "int",
    "struct",
    "break",
    "else",
    "long",
    "switch",
    "case",
    "enum",
    "register",
    "typedef",
    "char",
    "extern",
    "return",
    "union",
    "const",
    "float",
    "short",
    "unsigned",
    "continue",
    "for",
    "signed",
    "void",
    "default",
    "goto",
    "sizeof",
    "volatile",
    "do",
    "if",
    "static",
    "while"};

int main()
{
    gets(A);
    lexicalAnalyzer(A);

    return 0;
}

void lexicalAnalyzer(char S[]){
    i=0;

    while(S[i]){
        if(isIdent(S[i])){
            while(isIdent(S[i])){
                ident[idi][idj] = S[i];
                idj++;
                i++;
            }
            ident[idi][idj] = '\0';
            idi++;
            idj=0;
        } else if(isOperator(S[i])){
            while(isOperator(S[i])){
                oper[opi][opj] = S[i];
                opj++;
                i++;
            }
            oper[opi][opj] = '\0';
            opi++;
            opj=0;
        } else if(isDel(S[i])){
            while(isDel(S[i])){
                delim[deli][delj] = S[i];
                delj++;
                i++;
            }
            delim[deli][delj] = '\0';
            deli++;
            delj=0;
        } else{
            i++;
        }
    }

    isKeyword();

    printf("\nIdentifier\n-------------------\n");
    for(i=0; i<=idi; i++)
        printf("%s\n", ident[i]);

    printf("Operator\n-------------------\n");
    for(i=0; i<=opi; i++)
        printf("%s\n", oper[i]);

    printf("Delimiter\n-------------------\n");
    for(i=0; i<=deli; i++)
        printf("%s\n", delim[i]);

    printf("Keywords\n-------------------\n");
    for(i=0; i<=c; i++)
        printf("%s\n", keyword[i]);
}

int isIdent(char ch){
    if(isAlpha(ch) || isAlpha(ch) || isDigit(ch) || ch=='_'){
        return 1;
    } else{
        return 0;
    }
}

int isAlpha(char ch){
    if((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')){
        return 1;
    } else{
        return 0;
    }
}

int isDigit(char ch){
    if(ch >= '0' && ch <= '9'){
        return 1;
    } else{
        return 0;
    }
}

int isOperator(char ch){
    for(k = 0; k < 8; k++)
        if(ch == op[k])
            return 1;

    return 0;
}

int isDel(char ch){
    for(k = 0; k < 8; k++)
        if(ch == del[k])
            return 1;

    return 0;
}

void isKeyword(){
    for(i = 0; i < idi; i++){
        for(j = 0; j < 32; j++){
            if(!strcmp(ident[i], kword[j])){
                strcpy(keyword[c++], ident[i]);
            }
        }
    }
}