C program to classify lexemes

#include<stdio.h>

char lex[1000];
int n = 0;
int classify(char c){
    if(c == '\0') return 0;
    if(('a' <= c &&  c <= 'z') || ('A' <= c && c <= 'Z')) return 1;
    if('0' <= c && c <= '9') return 2;
    if(c == '+' || c == '-' || c == '*' || c == '/' || c == '%') return 3;
    if(c == '&' || c == '|' || c == '^') return 4;
    if(c == '>' || c == '<' || c == '!') return 5;
    if(c == '=') return 6;
    if(c == ';') return 7;
    if(c == '.') return 8;
    if(c == ',') return 9;
    if(c == '"') return 10;
}


void helper(){
    printf("Entered String : %s\n", lex);
    // int n = sizeof(lex);
    int first = classify(lex[0]);
    if(first == 10){
        printf("String %s is identified\n", lex);
    }else if(n == 1){
        if(first == 1){
            printf("Identifier %s is identified\n", lex);
        }else if(first == 2){
            printf("Number %s is identified\n", lex);
        }else if(first == 3){
            printf("Arithmetic Operator %s is identified\n", lex);
        }else if(first == 4){
            printf("Bitwise Operator %s is identified\n", lex);
        }else if(first == 6){
            printf("Assignment Operator %s is identified\n", lex);
        }else if(first == 7){
            printf("Semicolon %s is identified\n", lex);
        }else if(first == 8){
            printf("Dot Operator %s is identified\n", lex);
        }else if(first == 9){
            printf("Comma , separator is identified\n");
        }
        return;
    }
    if(lex[0] == 'p'){
        int x = classify(lex[1]);
        if(lex[1] == 'u'){
            if(lex[2] == 'b'){
                if(lex[3] == 'l'){
                    if(lex[4] == 'i'){
                        if(lex[5] == 'c'){
                            printf("Access Specifier : %s is identified\n");
                        }else{
                            printf("Identifier %s is identified\n", lex);
                        }
                    }else{
                        printf("Identifier %s is identified\n", lex);
                    }
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
            return;
        }
        if(lex[1] == 'r'){
            if(lex[2] == 'o'){
                if(lex[3] == 't'){
                    if(lex[4] == 'e'){
                        if(lex[5] == 'c'){
                            if(lex[6] == 't'){
                                if(lex[7] == 'e'){
                                    if(lex[8] == 'd' && lex[9] == '\0'){
                                        printf("Access Specifier : %s is identified\n");
                                    }else{
                                        printf("Identifier %s is identified\n", lex);
                                    }
                                }else{
                                    printf("Identifier %s is identified\n", lex);
                                }
                            }else{
                                printf("Identifier %s is identified\n", lex);
                            }
                        }else{
                            printf("Identifier %s is identified\n", lex);
                        }
                    }else{
                        printf("Identifier %s is identified\n", lex);
                    }
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else if(x == 2){
            printf("Identifier %s is identified\n", lex);
        }
        return;
    }
    if(lex[0] == 's'){
        if(lex[1] == 't'){
            if(lex[2] == 'a'){
                if(lex[3] == 't'){
                    if(lex[4] == 'i'){
                        if(lex[5] == 'c' && lex[6] == '\0'){

                        }else{
                            printf("Identifier %s is identified\n", lex);
                        }
                    }else{
                        printf("Identifier %s is identified\n", lex);
                    }
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else{
            printf("Identifier %s is identified\n", lex);
        }
        return;
    }
    if(lex[0] == 'c'){
        if(lex[1] == 'l'){
            if(lex[2] == 'a'){
                if(lex[3] == 's'){
                    if(lex[4] == 's' && lex[5] == '\0'){
                        printf("Keyword %s is identified\n", lex);
                    }else{
                        printf("Identifier %s is identified\n", lex);
                    }
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else if(lex[1] == 'h'){
            if(lex[2] == 'a'){
                if(lex[3] == 'r' && lex[4] == '\0'){
                    printf("Primitive datatype %s is identified\n", lex);
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else{
            printf("Identifier %s is identified\n", lex);
        }
        return;
    }
    if(lex[0] == 'i'){
        if(lex[1] == 'f' && lex[2] == '\0'){
            printf("Conditional %s statement is identified\n", lex);
        }else if(lex[1] == 'n'){
            if(lex[2] == 't' && n == 3){
                printf("Primitive datatype %s is identified\n", lex);
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else{
            printf("Identifier %s is identified\n", lex);
        }
    }
    if(lex[0] == 'd'){
        if(lex[1] == 'o'){
            if(n == 2){
                printf("Loop construct %s is identified\n", lex);
                return;
            }
            if(lex[2] == 'u'){
                if(lex[3] == 'b'){
                    if(lex[4] == 'l'){
                        if(lex[5] == 'e' && lex[6] == '\0'){
                            printf("Primitive datatype %s is identified\n", lex);
                        }else{
                            printf("Identifier %s is identified\n", lex);
                        }
                    }else{
                        printf("Identifier %s is identified\n", lex);
                    }
                }else{
                    printf("Identifier %s is identified\n", lex);
                }
            }else{
                printf("Identifier %s is identified\n", lex);
            }
        }else{
            printf("Identifier %s is identified\n", lex);
        }
        return;
    }


    if(first == 2){
        int idx = 0;
        int t = 1;
        while(lex[idx] != '\0') if(classify(lex[idx++]) != 2){ t = 0; break;}
        if(t){
            printf("Number %s is identified\n", lex);
        }else{
            if(idx > 0 && idx < n && lex[idx-1] == '.'){
                t = 1;
                while(lex[idx] != '\0') if(classify(lex[idx++]) != 2){ t = 0; break;}
                if(t){
                    printf("Floating point number is identified\n");
                }else{
                    if(idx > 0 && idx < n && lex[idx-1] == 'e'){
                        t = 1;
                        while(lex[idx] != '\0') if(classify(lex[idx++]) != 2){ t = 0; break;}
                        if(t){
                            printf("Scientific notation\n");
                        }else{
                            printf("Cannot determine this\n");
                        }
                    }else{
                        printf("Cannot determine this\n");
                    }
                }
            }else{
                printf("Cannot determine this %s\n", lex);
            }
        }
    }
}

int main(){
    while(1){
        int i = 0;
        char c ;
        while((c = getchar()) != '\n'){
            lex[i++] = c;
        }
        lex[i] = '\0';
        n = i;
        helper();
    }
    return 0;
}