Password Checker

//  Password Checker
//  Date: 10.12.19
#include<stdio.h>
#include<ctype.h>
//  ctype.h header file is used to use all the test functions

int main(){
    printf("=====Welcome To Password Checker=====\n\n");
    char password[20];
    printf("Enter your password: ");
    gets(password);
    int strength = 0, length = 0, i;
    int capital = 0, small = 0, special = 0, number = 0;

    for(i = 0; password[i] != '\0'; i++){
        //  Check if character is lowercase
        if(islower(password[i])){
            small = 1;
        }
        //  Check if character is uppercase
        else if(isupper(password[i])){
            capital = 1;
        }
        //  Check if character is number
        else if(isdigit(password[i])){
            number = 1;
        }
        //  Check if character is any special character
        else if(ispunct(password[i])){
            special = 1;
        }
        length++;
    }
    if(capital) strength++;
    if(small) strength++;
    if(special) strength++;
    if(number) strength++;
    if(length >= 8) strength++;

    if(strength <= 3) printf("\nPassword is weak.\n");
    else if(strength == 4) printf("\nPassword is medium.\n");
    else if(strength == 5) printf("\nPassword is strong.\n");
}
//  Do a little bit of research on it.
//  Still not clear then ask.
//  Try not to memorize but to understand.