如何在C++中聲明字符串和整數數組？

Question

#include <iostream> 
using namespace std; 

int main() 
{ 
// Declare variable 
    ifstream inFile; 
// Declare constant 
    const int MAX = 600; 
// Declare an array of strings named name that holds up to MAX 
    string array [name] = MAX; 
// Declare an array of whole numbers named grade that holds up to MAX 
    double array [grade] = MAX; 
// Declare variables quantity, x, avg, and sum (initialized to zero) that hold whole numbers 
    int sum = 0, avg, x, quantity; 
// Open input file 
    inFile.open("indata3.txt"); 
// Check if the file was opened 
    if (!inFile) 
    { 
    cout << "File was not found!" << endl; 
    return 1; 
    } 
// Set x to 0 
    x = 0; 
// Read name and grade from the file and assign them to name[x] and grade[x] respectively 
    cin >> name[x]; 
    cin >> grade[x]; 
// While (not-end-of-file) 
    while(inFile) 
    { 
//Increment x 
    x++; 
// Read a name and a grade from the file and assign them to name[x] and grade[x] respectively 
    cin >> name[x]; 
    cin >> grade[x]; 
    } 
// Print message 
    cout << "Enter quantity of grades to be processed (0-" << x << "): " << endl; 
// Read a value from the keyboard and assign it to quantity 
    cin >> quantity; 
// For (x = 0 to quantity-1) 
    for (x = 0; x <= quantity-1) 
    { 
//16. Accumulate grade[x] in sum 

    } 
// Assign to avg the value returned by average (sum, quantity) 
    avg = sum/quantity; 
// Print "Average grade: ", avg 
    cout << "Average grade: " << avg << endl; 
// Print "Name", "Grade", " Comment" 
    cout << "Name" << "," << "Grade" << "," << " Comment" << endl; 
// For (x = 0 to quantity-1) 
    for (x = 0; x <= quantity-1) 
{ 
// Print name[x], grade[x] 
    cout << name[x] << ", " << grade[x] << endl; 
// If (grade[x] < avg) 
    if (grade[x] < avg) 
    { 
// Print " below average" 
    cout << " below average" << endl; 
    } 
// Else if (grade[x] > avg) 
    else if (grade[x] > avg) 
    { 
// Print " above average" 
    cout << " above average" << endl; 
    } 
// Else 
    else() 
    { 
// Print " average" 
    cout << " average" << endl; 
    } 
} 
// Close the file. 
    inFile.close(); 

return 0; 
} 

以下是我們在20中的一些錯誤。大多數重複未聲明的標識符。也不知道在哪裏我需要添加更多的大括號來使它在語法上是正確的。還有一件事..我如何積累等級[x]成爲總和？任何幫助將不勝感激，謝謝。

error C2065: 'name' : undeclared identifier 
error C2075: 'array' : array initialization needs curly braces 
error C2065: 'grade' : undeclared identifier 
error C2371: 'array' : redefinition; different basic types 
error C2440: 'initializing' : cannot convert from 'const int' to 'double [1]' 
error C2228: left of '.open' must have class/struct/union1> type is 'int' 
error C2143: syntax error : missing ';' before ')' 
error C2059: syntax error : ')' 
error C2143: syntax error : missing ';' before '{' 
error C2228: left of '.close' must have class/struct/union1> type is 'int' 

Answer 1

希望這有助於一點點... ...（和建議得到一個C++的書和參考資料）

您的許多變量在使用前沒有聲明。

如 '姓名' 必須是：string name[];

讓我們來看看下面的語句：

string array [name] = MAX;

看起來你並不完全熟悉C++。

「String」是數據類型。 「數組」是數組的實際名稱。

「name」是一個未聲明的變量，並且必須是一個整數才能起作用。

「MAX」是一個常數。（你是好那裏。）

從你寫的方式，我猜你想擁有的串並聯陣列和雙所謂的「名稱「和」等級「，共600個元素。

在C++中，將被寫成：

string name[MAX]; // this creates an empty string array of 600 elements

和檔次是： double grade[MAX]; // this creates an empty double array of 600 elements

從您的代碼下面這部分不會有幾個原因的工作：

// Open input file inFile.open("indata3.txt"); // Check if the file was opened if (!inFile) { cout << "File was not found!" << endl; return 1; } // Set x to 0 x = 0; // Read name and grade from the file and assign them to name[x] and grade[x] respectively cin >> name[x]; cin >> grade[x]; // While (not-end-of-file) while(inFile) { //Increment x x++; // Read a name and a grade from the file and assign them to name[x] and grade[x] respectively cin >> name[x]; cin >> grade[x]; }

有幾個原因是：

1. while(not-end-of-file)是不是真正的代碼，你想：while(!inFile.eof())

2. cin >> name[x];從未訪問文件，並且永遠不會賦值給一個元素

祝你好運！ Google是你的朋友！讓人們知道你是一個新手，所以他們不會把你分開在堆棧溢出！獲得像dev ++或CLion這樣的好IDE。

Answer 2

array不是C++中的關鍵字。

如果要聲明字符串數組，可容納最大值= MAX，那麼你應該試試這個

字符串名稱[MAX]。

其中「name」是字符串數組的名稱，MAX是數組可以存儲的字符串的總數。

同爲整數，你應該使用

雙級[MAX]。

其中grade是整數數組的名稱。