Question

最近几天我一直在尝试调试该程序，但是我仍然找不到解决方案，因此希望您能为我提供帮助。

该程序应打印选举的获胜者。我只被分配用于实现print_winner和表决功能。

如果输入的名称与选举中候选人的姓名之一（候选人是命令行参数）匹配，则表决功能应更新该候选人的投票总数以计入新的投票并返回true。如果不是，则应返回false。问题似乎只是在计票时，布尔值部分工作正常。

print_winner函数应打印出在选举中获得最多选票的候选人的姓名，然后打印换行符。

这是我的代码：

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

// Max number of candidates
#define MAX 9

// Candidates have name and vote count
typedef struct {
    string name;
    int votes;
} candidate;

// Array of candidates
candidate candidates[MAX];

// Number of candidates
int candidate_count;

// Function prototypes
bool vote(string name, int argc, string argv[]);
void print_winner(string name, string argv[], int argc, int voter);

int main(int argc, string argv[]) {
    string name;
    // Check for invalid usage
    if (argc < 2) {
        printf("Usage: plurality [candidate ...]\n");
        return 1;
    }

    // Populate array of candidates
    candidate_count = argc - 1;
    if (candidate_count > MAX) {
        printf("Maximum number of candidates is %i\n", MAX);
        return 2;
    }
    for (int i = 0; i < candidate_count; i++) {
        candidates[i].name = argv[i + 1];
        candidates[i].votes = 0;
    }

    int voter_count = get_int("Number of voters: ");

    // Loop over all voters
    for (int i = 0; i < voter_count; i++) {
        name = get_string("Vote: ");

        // Check for invalid vote
        if (!vote(name, argc, argv)) {
            printf("Invalid vote.\n");
        }
    }

    // Display winner of election
    print_winner(name, argv, argc, voter_count);
}

// Update vote totals given a new vote
bool vote(string name, int argc, string argv[]) {
    // TODO
    int voter_count = argc - 1;
    int i, j;
    candidate f[candidate_count];
    for (i = 0; i < voter_count; i++) {
        f[i].name = name;
        f[i].votes = 0;
        for (j = 1; j < argc; j++) {
            if (strcmp(name, argv[j]) == 0) {
               return true;
               f[i].votes = 1;
            }
        }
    }
    for (i = 0; i < voter_count; i++) {
        for (j = 0; j < voter_count; j++) {
            if (i != j) {
                if (strcmp(f[i].name, f[j].name) == 0) {
                    f[i].votes = f[i].votes + 1;
                }
            }
        }
    }
    return false;
}

// Print the winner (or winners) of the election
void print_winner(string name, string argv[], int argc, int voter) {
    // TODO
    int voter_count = argc - 1;
    int i, j;
    candidate f[candidate_count];
    for (i = 0; i < voter_count; i++) {
        f[i].name = name;
        f[i].votes = 0;
        for (j = 1; j < argc; j++) {
            if (strcmp(name, argv[j]) == 0) {
               f[i].votes = 1;
            }
        }
    }
    for (i = 0; i < voter_count; i++) {
        for (j = 0; j < voter_count; j++) {
            if (i != j) {
                if (strcmp(f[i].name, f[j].name) == 0) {
                    f[i].votes = f[i].votes + 1;
                }
            }
        }
    }
    int max = f[0].votes;
    j = 0;
    for (i = 1; i < voter_count; i++) {
        if (f[i].votes > max) {
            max = f[i].votes;
            j = i;
        }
    }
    for (i = 0; i < voter_count; i++) {
        if (max == f[i].votes) {
            printf("%s\n", f[i].name);
        }
    }
    return;
}

Answer 1

这是您的代码中的一些问题：

函数vote()和print_winner()不应采用argc和argv，而应在全局数组candidates上运行。
此外，一个循环就足以处理投票，而且确定获胜者也很简单。 vote()和print_winner()中的代码太复杂，无法处理任何有意义的数据。

这是修改后的版本：

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

// Max number of candidates
#define MAX 9

// Candidates have name and vote count
typedef struct {
    string name;
    int votes;
} candidate;

// Array of candidates
candidate candidates[MAX];

// Number of candidates
int candidate_count;

// Function prototypes
bool vote(string name);
void print_winners(void);

int main(int argc, string argv[]) {
    // Check for invalid usage
    if (argc < 2) {
        printf("Usage: plurality candidate [...]\n");
        return 1;
    }

    // Populate array of candidates
    candidate_count = argc - 1;
    if (candidate_count > MAX) {
        printf("Maximum number of candidates is %i\n", MAX);
        return 2;
    }
    for (int i = 0; i < candidate_count; i++) {
        candidates[i].name = argv[i + 1];
        candidates[i].votes = 0;
    }

    int voter_count = get_int("Number of voters: ");

    // Loop over all voters
    for (int i = 0; i < voter_count; i++) {
        string name = get_string("Vote: ");

        // Check for invalid vote
        if (!vote(name)) {
            printf("Invalid vote: %s\n", name);
        }
    }

    // Display winner of election
    print_winners();
    return 0;
}

// Update vote totals given a new vote
bool vote(string name) {
    for (int i = 0; i < candidate_count; i++) {
        if (strcmp(candidates[i].name, name) == 0) {
            candidates[i].votes += 1;
            return true;
        }
    }
    return false; // no such candidate
}

// Print the winner (or winners) of the election
void print_winners(void) {
    int max_votes = 0;
    for (int i = 0; i < candidate_count; i++) {
        if (candidates[i].votes > max_votes) {
            max_votes = candidates[i].votes;
        }
    }
    for (int i = 0; i < voter_count; i++) {
        if (candidates[i].votes == max_votes) {
            printf("%s\n", candidates[i].name);
        }
    }
}

C.CS50 Purality任务，打印选举的获胜者

1 个答案: