c ++，“错误：聚合对象应初始化为'{…}'”

Question

编译此代码时，在函数调用中出现错误"Error: initialization with '{...}' expected for aggregate object" 。 我正在使用Visual Studio 11进行编译。

#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

您将在centerString中返回临时引用

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

centerStr是数组，不能将其用作函数

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

我想你是说

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

您可以尝试下面的示例函数，只需返回数组，RVO就可以启动。

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

永远不要使用本机数组，它们很糟糕，这就是它们的最糟糕的吸收方法之一。 基本上，这将要求数组具有合理的作用，而不能。 语言强制的错误基本上意味着它们无法完成您希望从任何其他数据类型中获得的全部功能，并且当您仅可以像使用 baus 一样使用std::array时，它们确实不值得花时间使用理智的人。

使用std::array并感谢甚至委员会也接受C数组。

有趣的是，我注意到您确实包含了<array> ，但随后没有使用std::array 。