Question

Imagine you are developing a software package that requires users to enter their own passwords. Read the input as a C-string or a string object. Your software requires that users’ passwords be sent to special functions that will verify if the characters used meet the following criteria:

• The password should be at least six characters long.

• The password should contain at least one uppercase and at least one lowercase letter.

• The password should have at least one digit.

Write a program that asks for a password then verifies that it meets the stated criteria. If it doesn’t, the program should display a message telling the user why.

You may consider using various functions such as the following ...

void displayRequirements();
void displayResult(char[]);
bool isValid(char[]);
bool hasLength(char[]);
bool hasLower(char[]);
bool hasUpper(char[]);
bool hasDigit(char[]);

or implement your own functional decomposition.

Sample Screen Output (user input in bold):

Password Requirements:
  - The password should be at least 6 characters long.
  - The password should contain at least one uppercase
    and at least one lowercase letter.
  - The password should have at least one digit.

Enter a password: srjc
The password is invalid.

It should be at least 6 characters long.
It should contain at least one uppercase letter.
It should have at least one digit.

Enter another password: srjc2020
The password is invalid.

It should contain at least one uppercase letter.

Enter another password: Srjc2020
The password is valid.

Process returned 0 (0x0)   execution time : 37.238 s
Press any key to continue.

Answer 1

/******************************************************************************

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Code, Compile, Run and Debug C program online.
Write your code in this editor and press "Run" button to compile and execute it.

*******************************************************************************/

#include <stdio.h>
#include <string.h>
#include <time.h>
#include<stdbool.h>
void displayRequirements() //function to display requirements
{
printf("\nPassword Requirements:");
printf("\n - The password should be at least 6 characters long.");
printf("\n- The password should contain at least one uppercase and at least one lowercase letter.");
printf("\n - The password should have at least one digit");
}
bool hasLower(char ch[100])
{
int count=0;
for(int i=0;i<strlen(ch);i++)
{
if(ch[i]>='a' && ch[i]<='z') //check for lower Case Character presence
count=1;
}
if(count==1)
return true;
else
return false;
}
bool hasUpper(char ch[100])
{
int count=0;
for(int i=0;i<strlen(ch);i++)
{
if(ch[i]>='A' && ch[i]<='Z') //check for Upper Case Character present
count=1;
}
if(count==1)
return true;
else
return false;
}
bool hasDigit(char ch[100])
{
int count=0;
for(int i=0;i<strlen(ch);i++)
{
if(ch[i]>='0' && ch[i]<='9') //check for digit
count=1;
}
if(count==1)
return true;
else
return false;
}
bool hasLength(char ch[100])
{
if(strlen(ch)>=6) //check if length is greater than 6
return true;
else
return false;
}
void displayResult(char pass[100])
{
  
bool invalid=true;
int error=0,k=0;
while(invalid) //while loop to run till the user enter a valid input
{
error=0; //reset error value with every iteration
if(k>0) //check to see if user has entered password for first time to ask enter password again
{
printf("\nEnter another password: ");
scanf("%s",pass);
}
if(!hasLength(pass)) //check password length if true below checks are performed
{
if(error==0) // if there is no error before displaying invalid password
{
error=1;
printf("The password is invalid.\n\n");
}
printf("It should be at least 6 characters long.\n");
}
if(!hasLower(pass)) // check to see if password has a lowercase character
{
if(error==0) // if there is no error before displaying invalid password
{
error=1;
printf("The password is invalid.\n\n");
}
printf("It should contain at least one lowercase letter.\n");
}
if(!hasUpper(pass)) //check to see if there is a uppercase character
{
if(error==0)
{
error=1; // if there is no error before displaying invalid password
printf("The password is invalid.\n\n");
}
printf("It should contain at least one uppercase letter.\n");
}
if(!hasDigit(pass)) //check to see if password has a digit
{
if(error==0)
{
error=1;
printf("The password is invalid.\n\n");
}
printf("It should have at least one digit.\n");
}
if(error==0) //if there is no error password is valid
{
printf("The password is valid.\n\n");   
invalid=false;
}
k++; //k increased to check if it first input entry
}
  
}
int main()
{

char pass[100];
  
clock_t ts=clock; //start time to calculate Execution time Taken
displayRequirements(); // display Requirement to User
printf("\n\nEnter a password: ");
scanf("%s",pass); // Taking user input
displayResult(pass); //Display Result to user
  
clock_t t = clock() ; //Calculating time after exection
double time_taken = ((double)ts-t)/CLOCKS_PER_SEC;
printf("\nProcess returned 0 (0x0) execution time : %f s",time_taken);

return 0;
}