这个C ++映射有什么问题？ [英] What is wrong with this C++ map?

问题描述

我想能够通过文本字符串调用特定的矩阵。我试图设置一个地图来做到这一点，但我没有很好的。

I would like to be able to call specific matrices by a text string. I am trying to set up a map to do this, but I do not have it quite right.

我注意到，如果我引用矩阵我试图操纵通过它的映射名称，它似乎工作（即， signalIndex [T2]。signal [i] [0] = 10），但是如果我尝试引用地图标签指向的矩阵，它不工作。有任何建议吗？

I notice that if I refer to the matrix I am trying to manipulate by its map name, it seems to work (i.e., signalIndex["T2"].signal[i][0]=10), however if I try to refer to the matrix that the map label is pointing to, it does not work. Any suggestions?

#include <iostream>
#include <map>
using namespace std;

struct signalGrid{
    double signal[20][200];
    signalGrid();
};


void mapTest(std::map<string,signalGrid> &temp_map);
map<string,signalGrid> signalIndex;
signalGrid testGrid1,testGrid2;


int main(){
    int i;

    signalGrid tempGrid;
    mapTest(signalIndex);

    tempGrid=signalIndex["T1"];
    for(i=0;i<5;i++){
        tempGrid.signal[i][0]=5;}

    for(i=0;i<5;i++){
        cout<<"TEST="<<tempGrid.signal[i][0]<<"\n";}
    for(i=0;i<5;i++){
        cout<<"TEST="<<testGrid1.signal[i][0]<<"\n";}
    for(i=0;i<5;i++){
        cout<<"TEST2="<<signalIndex["T1"].signal[i][0]<<"\n";}

    for(i=0;i<5;i++){
        signalIndex["T2"].signal[i][0]=10;}
    for(i=0;i<5;i++){
        cout<<"TEST3="<<testGrid2.signal[i][0]<<"\n";}
    for(i=0;i<5;i++){
        cout<<"TEST4="<<signalIndex["T2"].signal[i][0]<<"\n";}
    return 0;   
}


void mapTest(std::map<string,signalGrid> &temp_map){

    temp_map["T1"]=testGrid1; 
    temp_map["T2"]=testGrid2; 
    return; 
}

signalGrid::signalGrid(){
    int i,j;
    for(i=0;i<20;i++){
        for(j=0;j<200;j++){
            signal[i][j]=0;}}
}

推荐答案

tempGrid=signalIndex["T1"];

修改tempGrid不会更新映射中的相应矩阵

modifiying tempGrid won't update the corresponding matrix in the map

这篇关于这个C ++映射有什么问题？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！