CS50 - PSET2

Ceasar.c

#include <stdio.h>
#include <ctype.h>
#include <cs50.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, string argv[])
{
    if (argc == 2)  // needs a character to start, else return error message 
    {
        for (int j = 0; j < strlen(argv[1]); j++) // go through every character of argv 1
        {
            if (isdigit(argv[1][j] == ! 0)) // if its not a number 
            {
                printf("Usage: ./caesar key\n"); //return error message
                return 1; 
            }
    
            
            else  //if its a number
            {
                int k = atoi(argv[1]); //convert user input to an integar k  // convert the string entered into integar
                string plaintext = get_string("Plain text: "); //ask user for plain text
                printf("ciphertext:  ");
        
                for (int i = 0; i < strlen(plaintext); i++) //go through every letter of the plain text
                {
                    if (plaintext[i] >= 'a' && plaintext[i] <= 'z')  // if smallercase, then print using the modulo equation
                    {
                        char c = ((plaintext[i] - 'a')  + k) % 26 + 'a'; //covert from ascii to 0-26 scale, modulo to wrap aroud alphapet
                        printf("%c", c);
                    }
                    else if (plaintext[i] >= 'A' && plaintext[i] <= 'Z') //if uppercase, then print using the moduo equation
                    {
                        char C = ((plaintext[i] - 'A')  + k) % 26 + 'A'; // see line 19
                        printf("%c", C);
                    }
                    else
                    {
                        printf("%c", plaintext[i]); // if it is not uppercase or lowercase, print as is
                    }
                }
                printf("\n");
                return 0;
            }
        } 
    }
    else
    {
        printf("Usage: ./caesar key\n"); //user puts something other than an integer print message
        return 1; 
    }
}

Readability.c

#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <math.h>

int main(void)
{
    string text = get_string("Text: "); // ask user for input
    int letterscount = 0;  // decalare variables 
    int wordcount = 1;
    int sentencecount = 0;

    for (int i = 0; i < strlen(text); i++) // run loop to count variables
    {
       if ((text[i] >= 'a' && text[i] <= 'z') || (text[i] >= 'A' && text[i] <= 'Z'))
       {
           letterscount++;
       }
       else if (text[i] == ' ')
       {
           wordcount++;
       }
       else if (text[i] == '.' || text[i] == '!' || text[i] == '?')
       {
           sentencecount++;
       }
    }


    float grade = 0.0588 * (100 * (float) letterscount / (float) wordcount) - 0.296 * (100 * (float) sentencecount / (float) wordcount) - 15.8;
    if (grade < 16 && grade >= 0)
    {
        printf("Grade %i\n", (int) round(grade));
    }
    else if (grade >= 16)
    {
        printf("Grade 16+\n");
    }
    else
    {
        printf("Before Grade 1\n");
    }

}