关于 for 循环内函数调用的问题

Question

I am writing a simple code that runs a plurality vote. My code seems to work only if I don't call the bool vote function after char *name = get_string("Vote: ") Why is this the case? The logic that I don't understand is that char *name changes every time a new value is assigned with get_string n number times in the for loop. If this is the case, shouldn't it logically make sense to call the vote function for each name before a new value is assigned to name? Why doesn't the code work after I add a line that calls the vote function before each iteration of the for loop?

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

// Max number of candidates
#define MAX 9

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

// Array of candidates
candidate candidates[MAX];

// Number of candidates
int candidate_count;
int voter_count;

// Function prototypes
bool vote(char *name);
void print_winner(void);

int main(int argc, char *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;
        printf("%s\n", candidates[i].name);
    }

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

    // Loop over all voters
    for (int i = 0; i < voter_count; i++)
    {
        char *name = get_string("Vote: ");
        //The main difference between the answer and my code was that I tried to call vote(name) at this point. I should figue out why this is incorrect, and the following logical explanation.

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

    // Display winner of election
    print_winner();
}

// Update vote totals given a new vote
bool vote(char *name)
{
    // TODO
    for (int i = 0; i < candidate_count; i++)
    {
        if (strcmp(candidates[i].name, name) == 0)
        {
            candidates[i].votes++;
            return true;
        }
    }
    return false;
}

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

Answer 1

Besides the fact that the spec says " You should not modify anything else in plurality.c ", there already is a call to vote(name) for each voter here if (!vote(name)) .

It does not " logically make sense to call the vote function for each name before a new value is assigned to name " because the order of operations is:

• get a candidate name for voter i
• add that vote to the selected candidate