Question

基本上问题是findLowest函数没有按照我的计划做它。我知道这是一个逻辑错误，但我似乎无法找出变量没有更新的原因。它们总是默认使用它们实例化的值。

#include <stdafx.h>
#include <string>
#include <iostream>

using namespace std;

//Function prototypes
void findLowest(int regAccidents[], int arraySize, string regNames[]);
int getNumAccidents(string);
const int NUM_REGIONS = 5;

int main(){
    string regionNames[NUM_REGIONS] = { "North", "South", "East", "West", "Central" };
    int regionAccidents[NUM_REGIONS];

    for (int i = 0; i < NUM_REGIONS; i++){//Populates the accident array
        regionAccidents[i] = getNumAccidents(regionNames[i]);

        if (regionAccidents[i] < 0)//checks to see if there are any accidents counts lower than 0
            regionAccidents[i] = 0;
        }

        findLowest(regionAccidents, NUM_REGIONS, regionNames);
}

int getNumAccidents(string region){//returns the accidents for a specific region to be assigned to the regionAccidents[] array in main()

    int regionAccidents = 0;
    cout << "How many accidents for " << region << "? ";
    cin >> regionAccidents;
    return regionAccidents;

}

void findLowest(int regAccidents[], int arraySize, string regNames[]){  //used to determine what the lowest number of accidents is
    int lowest = regAccidents[0];                                       //once that is found, update the lowRegion string of the accident location
    string lowRegion = regNames[0];
    for (int i = 0; i < arraySize; i++){
        if (regAccidents[i] < regAccidents[i++]){
            lowest = regAccidents[i];
            lowRegion = regNames[i];
        }
    }

    cout << "The region with the lowest amount of accidents is: " << lowRegion << endl;
    cout << "The lowest number of accidents is: " << lowest << endl;
}

Answer 1

if (regAccidents[i] < regAccidents[i++]) { ...

是错误的，您需要将当前索引与目前为止找到的最低值进行比较：

if (regAccidents[i] < lowest) { ...

表达式regAccidents[i] < regAccidents[i++]将从不为真，因为您正在比较数组中的相同项目。然而，当你最不期望它时，会增加i。这并不重要，因为这是你的主要问题完全隐藏的次要问题： - ）

Answer 2

是的，您的代码中存在逻辑错误。 findLowest应如下所示：

int lowest = regAccidents[0];       
string lowRegion = regNames[0];
for (int i = 1; i < arraySize; i++){
        //^^you have initialized lowest as regAccidents[0], so search from 1
    if (regAccidents[i] < lowest ){
        //^^if current is smaller than lowest, update lowest and name    
        lowest = regAccidents[i];
        lowRegion = regNames[i];
    }
}

Answer 3

你确实对现在输出的内容说了什么。你用这条线的增量超越了数组吗？

if（regAccidents [i]＆lt; regAccidents [i ++]）

逻辑流程for循环

3 个答案: