![](/img/trans.png)
[英]CS50 pset3 Plurality: why does vote function not return false when given invalid candidate?
[英]Plurality, cs 50, Why printf function prints differently outside if statement?
我知道 print_winner function 的實現不正確(printf 應該在 if 語句中)。 但是,我無法弄清楚為什么 printf 在放置在 if 語句之外時會以不同的方式打印名稱?
如果我將 printf 放在 if 語句之外,這里是代碼和 output
代碼:
// Print the winner (or winners) of the election
void print_winner(void)
{
int maximum = candidates[0].votes;
string winner = candidates[0].name;
for (int h = 0; h < candidate_count; h++)
{
if (candidates[h].votes > maximum)
{
maximum = candidates[h].votes;
}
}
for (int k = 0; k < candidate_count; k++)
{
if (candidates[k].votes == maximum)
{
winner = candidates[k].name;
}
printf("%s\n", winner);
Output:
~/pset3/plurality/ $ ./test sonya criss ben anbu
Number of voters: 4
Vote: ben
Vote: ben
Vote: anbu
Vote: anbu
sonya
sonya
ben
anbu
如果我將 printf 放在 if 語句中,這里是代碼和 output:
代碼:
// Print the winner (or winners) of the election
void print_winner(void)
{
int maximum = candidates[0].votes;
string winner = candidates[0].name;
//Find maximum votes
for (int h = 0; h < candidate_count; h++)
{
if (candidates[h].votes > maximum)
{
maximum = candidates[h].votes;
winner = candidates[h].name;
}
}
//Find candidate with maximum votes
for (int k = 0; k < candidate_count; k++)
{
if (candidates[k].votes == maximum)
{
winner = candidates[k].name;
printf("%s\n", winner);
}
}
return;
}
Output:
~/pset3/plurality/ $ ./plurality sonya criss ben anbu
Number of voters: 4
Vote: ben
Vote: ben
Vote: anbu
Vote: anbu
ben
anbu
在您的第一種情況下,您打印的獲勝者名稱是 Candidate candidates[0].name
,它是sonia ,直到if (candidates[k].votes == maximum)
變為 true 並且您重新分配了獲勝者,並且您打印了 Candidate_count 次,因為無條件地在循環中。
在第二種情況下,您只打印投票數等於最大值的人的姓名( if (candidates[k].votes == maximum)
為真),因此只有同時獲得 2 票的ben和anbu 才是最大值。
因為幾個人可以擁有相同的票數,所以擁有可變的獲勝者是沒有用的,你可以這樣做
// Print the winner (or winners) of the election
void print_winner(void)
{
int maximum = candidates[0].votes; /* suppose candidate_count > 0, else initialize with -1 */
//Find maximum votes
for (int h = 1; h < candidate_count; h++) /* useless to redo at index 0 */
{
if (candidates[h].votes > maximum)
maximum = candidates[h].votes;
}
//Find candidate(s) with maximum votes
for (int k = 0; k < candidate_count; k++)
{
if (candidates[k].votes == maximum)
puts(candidates[k].name);
}
}
從你的言論
您能否詳細說明為什么在第一種情況下,在
if (candidates[k].votes
變為 true 之前,會打印出獲勝者的名字 Candidatecandidates[0].name
因為你用candidates[0].name;
初始化了獲勝者; 正在做:
字符串獲勝者=候選人[0].name;
並且僅當if (candidates[k].votes == maximum)
為真時才修改獲勝者:
if (candidates[k].votes == maximum) { winner = candidates[k].name;
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.