Let's walk through the problems in your code and fix them one by one to get your Scrabble scorer working correctly:

1. Core Switch Statement Error #

The primary compilation error comes from switch (word):

scrabble.c:50:9: error: statement requires expression of integer type ('string' (aka 'char *') invalid)
switch (word)
^ ~~~~

In C, the switch statement requires an integer-type expression (like char, int, etc.), but you're passing a string (which is a pointer to char). You should be checking individual characters in the word, not the entire string.

2. Invalid Case Labels #

Your case isupper(word[i]): syntax is incorrect. Case labels must be compile-time constants, but isupper() returns a runtime value (non-zero if true, 0 if false). This isn't allowed in switch cases—instead, use if/else checks for character casing, or normalize the character to lowercase/uppercase first.

3. Other Syntax & Logic Issues #

• Typos: Points should be POINTS (your score array is defined as uppercase POINTS), and Break needs to be lowercase break (C is case-sensitive).
• Incorrect ASCII Values: '65' and '97' are character literals for the digits '6'/'5' and '9'/'7'—you want the integer values 65 (ASCII for 'A') or, better yet, use 'A' directly for readability.
• Early Return: Your return score; is inside the for loop, so it will exit after the first character. Move it outside the loop to calculate the full word's score.
• Non-Alphabetic Characters: You didn't handle non-letters—we need to skip them instead of trying to score them.

Fixed Code #

Here's the corrected version of your code with all issues addressed:

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

// 字母表中每个字母对应的分值
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};

int compute_score(string word);

int main(void)
{
    // 获取两位玩家的输入单词
    string word1 = get_string("Player 1: ");
    string word2 = get_string("Player 2: ");

    // 计算两个单词的得分
    int score1 = compute_score(word1);
    int score2 = compute_score(word2);

    // 输出获胜方
    if (score1 > score2)
    {
        printf("Player 1 wins!\n");
    }
    else if (score1 < score2)
    {
        printf("Player 2 wins!\n");
    }
    else
    {
        printf("Tie!\n");
    }
}

int compute_score(string word)
{
    int score = 0;
    int length = strlen(word);
    for (int i = 0; i < length; i++)
    {
        char c = word[i];
        // 跳过非字母字符
        if (!isalpha(c))
        {
            continue;
        }
        // 统一转换为大写字母计算索引
        char upper_c = toupper(c);
        int index = upper_c - 'A';
        score += POINTS[index];
    }
    // 循环结束后返回总得分
    return score;
}

Key Improvements: #

• Replaced the invalid switch with isalpha() checks and case normalization using toupper()—this simplifies the code and avoids switch statement issues.
• Added handling for non-alphabetic characters with continue to skip them.
• Fixed typos and corrected the return statement placement.
• Used 'A' instead of hardcoded ASCII values for better readability.

内容的提问来源于stack exchange，提问作者JohnHann-123