CODEWITHSUNDEEP
arrayscstring
Aylin Naebzadeh
Aylin Naebzadeh

Reputation: 135

How to correspond numbers in the array to English alphabets?

I am learning about arrays and data types in C. My question is that how can I compute the sum of the chars of a string. The value of chars in POINTS array for example the value of A(or a) is 1 and B(or b) is 3 etc. Now my question is that how can tell my program that A is 1 because by default it is working with the asci table. I will be happy for your help.

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

// Points assigned to each letter of the alphabet
int POINTS[] = {1, 3, 3, 2, 1, 4, 2, 4, 1, 8, 5, 1, 3, 1, 1, 3, 10, 1, 1, 1, 1, 4, 4, 8, 4, 10};
/////////////// A  B  C  D . . .
int compute_score(string word);

int main(void)
{

    int score = compute_sum(Amazing!);
    //it must calculates 1 + 1 + 1 + 10 + 1 + 1 + 2 + 0
}

int compute_sum(string word)
{
    for(int i=0 ; i<strlen(word);i++)
    {
        //todo
    }
}

Upvotes: 0

Views: 1067

Answers (2)

Cheatah
Cheatah

Reputation: 1835

Generally speaking I would probably do something like this:

#include <stdio.h>
#include <stdint.h>
#include <string.h>

static const int points[UINT8_MAX + 1] = {
    ['a'] = 1,
    ['b'] = 3,
    ['c'] = 3,
    ['d'] = 2,
    ['e'] = 1,
    ['f'] = 4,
    ['g'] = 2,
    ['h'] = 4,
    ['i'] = 1,
    ['j'] = 8,
    ['k'] = 5,
    ['l'] = 1,
    ['m'] = 3,
    ['n'] = 1,
    ['o'] = 1,
    ['p'] = 3,
    ['q'] = 10,
    ['r'] = 1,
    ['s'] = 1,
    ['t'] = 1,
    ['u'] = 1,
    ['v'] = 4,
    ['w'] = 4,
    ['x'] = 8,
    ['y'] = 4,
    ['z'] = 10,
};

static int compute_sum(const char *word)
{
    const unsigned char *c;
    int sum = 0;

    for (c = (const unsigned char *) word; *c; c++)
        sum += points[(int) *c];

    return sum;
}

int main(void)
{
    int score;

    score = compute_sum("Amazing!");

    printf("Score: %d\n", score);
}

Rationale: more readable, less error prone, no arithmetic needed, less chance of UB.

Upvotes: 3

Barmar
Barmar

Reputation: 780889

In ASCII and all character encodings derived from it (including Unicode) the letters in the Latin alphabet are all contiguous. So you can subtract the encoding of A or a from a letter to get its corresponding index.

int compute_sum(string word)
{
    int total = 0;
    for(int i=0 ; i<strlen(word);i++)
    {
        if (isupper(word[i])) {
            total += POINTS[word[i] - 'A'];
        } else if (islower(word[i])) {
            total += POINTS[word[i] - 'a'];
        }
    }
    return total;
}

Upvotes: 2

Related Questions