Answer to Question #157862 in C++ for Shehryar

Question

Initialize a string of size 40. Write a program that prints all unique alphabets from c-string. After printing them sort them in ascending order.

For example: Hi world I am here to help you.

Unique characters are: H, I, W, O, R, L, D, A, M, E, T, P, Y, U. Sorted: A, D, E, H, I, L, M, O, P, R, T, U, W, Y

Answer 1

Here is the code! Because c-strings are required, I mostly used c functions instead of c++ ones.

#include <cstdio>
#include <string>

//number of letters
const int SIZE = 'Z' - 'A' + 1;

int main()
{
    //get string
    char string[40];
    printf("Enter the string: ");
    fflush(stdout);
    scanf("%[^\n]", string);
    
    //letters, found in text
    bool meet[SIZE], first = true;
    for (int i = 0; i < SIZE; i++) meet[i] = false;
    
    printf("Unique characters are: ");
    
    //go through all letters
    for (int i = 0; i < 40 && string[i]; i++)
    {
        char c = toupper(string[i]);
        
        if (c >= 'A' && c <= 'Z' && !meet[c - 'A'])
        {
            if (first)
            {
                printf("%c", c);
                first = false;
            }
            else
                printf(", %c", c);
            
            meet[c - 'A'] = true;
        }
    }
    
    //sorted
    first = true;
    printf("\nSorted: ");
    
    for (int i = 0; i < SIZE; i++)
    {
        if (meet[i])
        {
            if (first)
            {
                printf("%c", i + 'A');
                first = false;
            }
            else
                printf(", %c", i + 'A');
        }
    }
    
    printf("\n");
    fflush(stdout);
    return 0;
}