C++错误：在"int"之前有预期的主表达式？

C++ error: expected primary-expression before 'int'?

本文关键字：表达式 错误 int C++      更新时间：2023-10-16

更新：所以我能够编译并运行这个程序，它似乎可以工作！然而，评判得分值2.3-的变量以一种奇怪的方式存储，并且正在放弃计算。当我输入2.3时，存储值是2.299999999998——为什么会这样？calcScore或最低和最高函数可能有错误，因为输入分数时最终分数相差0.3，2.3-5.5-5.5-8.5-有什么想法吗？

// file name starSearch.cpp
// author: SK
// last modified: 03/19/2012
#include <iostream> 
#include <iomanip>
using namespace std;
//function prototypes
void getJudgeData(double &);
void calcScore(double, double, double, double, double);
int findLowest(double, double, double, double, double);
int findHighest(double, double, double, double, double);
//declare variables
double score1;
double score2;
double score3;
double score4;
double score5;
int main()
{
    getJudgeData(score1); //Call getJudgeData for first judge score
    getJudgeData(score2); //Call getJudgeData for second judge score
    getJudgeData(score3); //Call getJudgeData for third judge score 
    getJudgeData(score4); //Call getJudgeData for fourth judge score
    getJudgeData(score5); //Call getJudgeData for fifth judge score
    calcScore(score1, score2, score3, score4, score5);    //calculate contestant score
    return 0; 
}
//
//Begin function prototypes definitions
//
//defines calcScore.
void calcScore(double score1, double score2, double score3, double score4, double score5)
{
    double total = (score1 + score2 + score3 + score4 + score5 - findLowest(score1, score2, score3, score4, score5) - findHighest(score1, score2, score3, score4, score5)) / 3;
    cout << setprecision(2);
    cout << "The contestant's final score is: " << total << endl;
}
//defines getJudgeData. this function asks each judge for their score.
void getJudgeData(double &score)
{
    cout << "Judge, enter the contestant's score: ";
    cin >> score;
    if (score < 0 || score > 10) //validate score between 0-10, else display error msg
    {
    cout << "ERROR: Enter a value in the range 0-10.n";
    return getJudgeData(score);
    }
    return;
}
//defines findLowest. this function returns the lowest score entered.
int findLowest(double score1, double score2, double score3, double score4, double score5)
{
    if (score1 < score2 && score1 < score3 && score1 < score4 && score1 < score5)
    {
        return score1;
    }
    else if (score2 < score1 && score2 < score3 && score2 < score4 && score2 < score5)
    {   
        return score2;
    }
    else if (score3 < score1 && score3 < score2 && score3 < score4 && score3 < score5)
    {
        return score3;
    }
    else if (score4 < score1 && score4 < score2 && score4 < score3 && score4 < score5)
    {
        return score4;
    }
    else if (score5 < score1 && score5 < score2 && score5 < score3 && score5 < score4)
    {
        return score5;
    }
}
//defines findHighest. this functio returns the highest score entered.
int findHighest(double score1, double score2, double score3, double score4, double score5)
{
    if (score1 > score2 && score1 > score3 && score1 > score4 && score1 > score5)
    {
        return score1;
    }
    else if (score2 > score1 && score2 > score3 && score3 > score4 && score3 > score5)
    {   
        return score2;
    }
    else if (score3 > score1 && score3 > score2 && score3 > score4 && score3 > score5)
    {
        return score3;
    }
    else if (score4 > score1 && score4 > score2 && score4 > score3 && score4 > score5)
    {
        return score4;
    }
    else if (score5 > score1 && score5 > score2 && score5 > score3 && score5 > score4)
    {
        return score5;
    }
}

原件：

我在第39行遇到编译器错误，我的代数表达式是用整数3写成的。我只是不知道如何将五个分数取平均值，去掉最低和最高的。不过，确定最高和最低的函数似乎是有序的。。请帮忙。

谢谢。

*// file name starSearch.cpp
// author: SK
// last modified: 03/19/2012
#include <iostream> 
using namespace std;
//function prototypes
void getJudgeData(double);
void calcScore();
int findLowest();
int findHighest();
//declare variables
double score1;
double score2;
double score3;
double score4;
double score5;
int main()
{
    getJudgeData(score1); //Call getJudgeData for first judge score
    getJudgeData(score2); //Call getJudgeData for second judge score
    getJudgeData(score3); //Call getJudgeData for third judge score 
    getJudgeData(score4); //Call getJudgeData for fourth judge score
    getJudgeData(score5); //Call getJudgeData for fifth judge score
    calcScore();    //calculate contestant score
    return 0; 
}
//
//Begin funtion prototypes definitions
//
//defines calcScore.
void calcScore(double score1, double score2, double score3, double score4, double score5)
{
    double total = score1 + score2 + score3 + score4 + score5 - int findLowest(a, b, c, d, e) - intfindHighest(a, b, c, d, e) / 3;
    cout << "The contestant's final score is: " << total << endl;
}
//defines getJudgeData. this function asks each judge for their score.
void getJudgeData(double score)
{
    cout << "Judge, enter the contestant's score: ";
    cin >> score;
    if (score < 0 || score > 10) //validate score between 0-10, else display error msg
    {
    cout << "ERROR: Enter a value in the range 0-10: ";
    cin >> score;
    }
    else
    return;
}
//defines findLowest. this function returns the lowest score entered.
int findLowest(double score1, double score2, double score3, double score4, double score5)
{
    if (score1 < score2, score3, score4, score5)
    {
        return score1;
    }
    else if (score2 < score1, score3, score4, score5)
    {   
        return score2;
    }
    else if (score3 < score1, score2, score4, score5)
    {
        return score3;
    }
    else if (score4 < score1, score2, score3, score5)
    {
        return score4;
    }
    else if (score5 < score1, score2, score3, score4)
    {
        return score5;
    }
}
//defines findHighest. this functio returns the highest score entered.
int findHighest(double score1, double score2, double score3, double score4, double score5)
{
    if (score1 > score2, score3, score4, score5)
    {
        return score1;
    }
    else if (score2 > score1, score3, score4, score5)
    {   
        return score2;
    }
    else if (score3 > score1, score2, score4, score5)
    {
        return score3;
    }
    else if (score4 > score1, score2, score3, score5)
    {
        return score4;
    }
    else if (score5 > score1, score2, score3, score4)
    {
        return score5;
    }
}*

函数分别称为findLowest和findHighest。int是它们的返回类型，在调用它们时不应指定。

如果这让你感到困惑，我建议你找一本好的C++入门级书籍，仔细阅读函数声明和调用。

除了您之前的回答之外，您的getJudgeData函数也非常坏。它需要使用双引用，否则您将永远不会修改原始变量，并且该函数毫无价值。此外，对于法官两次输入糟糕分数，您没有任何保护措施。

void getJudgeData(double& score)
{
    cout << "Judge, enter the contestant's score: ";
    cin >> score;
    if (score < 0 || score > 10) //validate score between 0-10, else display error msg
    {
        cout << "ERROR: Enter a value in the range 0-10: ";
        return getJudgeData(score);
    }
    return;
}

这种简单的递归将保护您免受法官每次输入错误数据的影响，而且它还将正确地修改原始变量，就像您的代码编写时所期望的那样。

除了Chowlett提供的答案外，您还需要重新考虑在findLowest和findHighest中使用逗号运算符。

例如，findHighest 中的行

if (score1 > score2, score3, score4, score5)

基本上与完全相同

if (score5)

这似乎不是你想要的。

问题出在您的线路上：

double total = score1 + score2 + score3 + score4 + score5 - int findLowest(a, b, c, d, e) - intfindHighest(a, b, c, d, e) / 3;

您不应该在内联中包含int标识符。编译器已经知道您的函数返回一个int。而是编写

double total = score1 + score2 + score3 + score4 + score5 - findLowest(a, b, c, d, e) - findHighest(a, b, c, d, e) / 3;

正如其他人指出的那样，你可能想把它变成替身。在这种情况下，你会这样做。

double total = score1 + score2 + score3 + score4 + score5 - (double)findLowest(a, b, c, d, e) - (double)findHighest(a, b, c, d, e) / 3;

不过，这实际上并不能计算平均值，所以应该使用括号来强制执行顺序或操作。

double total = (score1 + score2 + score3 + score4 + score5 - (double)findLowest(a, b, c, d, e) - (double)findHighest(a, b, c, d, e)) / 3;

您想在那里执行强制转换吗？这是用括号（double）完成的，我认为double也是你想要的，尽管我不确定那里是否需要它。

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