c ++，“錯誤：聚合對象應初始化為'{…}'”

Question

編譯此代碼時，在函數調用中出現錯誤"Error: initialization with '{...}' expected for aggregate object" 。 我正在使用Visual Studio 11進行編譯。

#include <iostream>
#include <string>
#include <array>
using namespace std;

typedef std::array<string, 5> string_t;
string_t centerString(std::array<string, 5> (&tempArray),unsigned short int length);
string_t evenString(std::array<string, 5> (&tempArray),unsigned short int length);

int main(){
    std::array<string, 5> aArray = {"a","aa","aaa","aaaa","aaaaa"};

    std::array<string, 5> evenStr[5] = evenString(aArray,5);
    std::array<string, 5> centerStr[5] = centerStr(aArray,5);
}


 string_t evenString(std::array<string, 5> (&srcArray),unsigned short int length){
     std::array<string, (sizeof(srcArray)/sizeof(srcArray[0]))> trgtArray= {};
     for(unsigned short int x = 0; x < (sizeof(srcArray)/sizeof(srcArray[0]));x++){
         trgtArray[x] = srcArray[x];
         for(unsigned short int y = 0; y < (length-trgtArray[x].length()); y++){
             trgtArray[x] += " ";
         }
     }

     return(trgtArray);
}

 string_t centerString(std::array<string, 5> (&srcArray),unsigned short int length){
     std::array<string, (sizeof(srcArray)/sizeof(srcArray[0]))> trgtArray= {};
     unsigned short int remainder;
     string spacer = "";
     for(unsigned short int x = 0; x < (sizeof(srcArray)/sizeof(srcArray[0]));x++){
         remainder = length - srcArray[x].length();
         if((remainder % 2) == 0){
            trgtArray[x] = srcArray[x];
            for(unsigned short int y = 0; y < (length-srcArray[x].length()); y++){
                trgtArray[x] += " ";
            }
         }else{
             for(unsigned short int z = 0; z < (remainder/2); z++){
                 spacer += " ";
             }
             trgtArray[x] = spacer + srcArray[x] + spacer + " ";
         }
     }

     return(trgtArray);
 }

Answer 1

您將在centerString中返回臨時引用

string_t& centerString(std::array<string, 5> (&tempArray),unsigned short int length);

centerStr是數組，不能將其用作函數

std::array<string, 5> centerStr = centerStr(aArray,5);

我想你是說

std::array<string, 5> centerStr = centerString(aArray,5);

您可以嘗試下面的示例函數，只需返回數組，RVO就可以啟動。

std::array<string,5> evenString(std::array<string, 5> (&srcArray), unsigned short length){
     std::array<string,5> trgtArray = {};
    //....
     return trgtArray;
}  

std::array<string, 5> evenStr = evenString(aArray,5);
std::array<string, 5> centerStr = centerString(aArray,5);

Answer 2

永遠不要使用本機數組，它們很糟糕，這就是它們的最糟糕的吸收方法之一。 基本上，這將要求數組具有合理的作用，而不能。 語言強制的錯誤基本上意味着它們無法完成您希望從任何其他數據類型中獲得的全部功能，並且當您僅可以像使用 baus 一樣使用std::array時，它們確實不值得花時間使用理智的人。

使用std::array並感謝甚至委員會也接受C數組。

有趣的是，我注意到您確實包含了<array> ，但隨后沒有使用std::array 。