C ++：运行程序时出现分段错误（从文件中输入数字到数组）

Question

I'm trying to input numbers from a text file. What I need to do is sort the numbers into an array that stores odd numbers, as well as one that stores even ones. From there, I just need to output the average, total, min, max, and then the numbers in the array that are greater than the average.

From researching, it's my understanding that a seg. fault occurs because of problems with memory allocation. I checked my arrays, and I don't think there should be a problem. The total amount of numbers in the file is 50, and so there should be room for the numbers, with what I allocated for my arrays in the beginning of main.

Here is my input file:

46 30 82 90 56 17 95 16 48 26 4 58 0 78 92 60 12 21 63 47 19 41 90 85 14 -9 52 71 79 16 80 51 95 102 34 10 79 95 61 92 89 88 66 64 92 63 66 64 39 5

I am using Linux, by the way.

#include <iostream>
#include <fstream>

using namespace std;

void oddOrEven(int [], int [], int [], ifstream &, int &, int &, int &);
void calcData(int [], int [], double &, double &, double &, double &, double &, int &, 
int &);

int main()
{

int i;
int a;
int b;
double totalEven = 0;
double totalOdd;
double average = 0;
double max = 0;
double min = 0;
int array[75] = {0};
int evenArray[50] = {0};
int oddArray[50] = {0};

ifstream fileIn;

fileIn.open("file.txt");

if (!fileIn){
cout << "\nError, could not open file.\n";
}

oddOrEven(array, evenArray, oddArray, fileIn, i, a, b);

calcData(evenArray, oddArray, totalEven, totalOdd, average, min, max, a, b);

fileIn.close();

return 0;

}

void oddOrEven(int array[], int evenArray[], int oddArray[], ifstream & fileIn, int & i, 
int & a, int & b){

while (fileIn >> i) {

fileIn>>array[i];

if (array[i] % 2 == 0){
evenArray[a]=array[i];
a++;
}

else{

oddArray[b] = array[i];
b++;

}}}

void calcData(int evenArray[], int oddArray[], double & totalEven, double & totalOdd,  
double & average, double & min, double & max, int & a, int & b){

//Find min, max, total and average for Even Array.

for (int i = 0; i < a; i++){

totalEven += evenArray[i];

if (i = 0){
min = evenArray[i];
max = evenArray[i];
}

if (evenArray[i] < min)
min = evenArray[i];

if (evenArray[i] > max)
max = evenArray[i];

}

average = totalEven/a;

cout << "\nMinimum is " << min;
cout << "\nMaximum is " << max;
cout << "\nTotal is " << min;
cout << "\nAverage is " << average;

//Numbers higher than the average for Even Array:

for (int k = 0; k < a; k++){
if (evenArray[k] > average/2)
cout << evenArray[k] << " ";
}

//Find min, max, total and average for Odd Array.

for (int i = 0; i < a; i++){

totalOdd += oddArray[i];

if (i = 0){
min = oddArray[i];
max = oddArray[i];
}

if (oddArray[i] < min)
min = oddArray[i];

if (oddArray[i] > max)
max = oddArray[i];

}

average = totalOdd/b;

cout << "\nMinimum is " << min;
cout << "\nMaximum is " << max;
cout << "\nTotal is " << min;
cout << "\nAverage is " << average;

//Numbers higher than the average for Odd Array:

for (int k = 0; k < b; k++){
if (oddArray[k] > average/2)
cout << oddArray[k] << " ";}
}

Answer 1

You use i , a and b to index into your arrays, but you never initialize them.

Also, the if (i = 0) should read if (i == 0) (a single = is assignment, not comparison).

I didn't read the code all that closely. There are probably other errors.

A couple of general recommendations:

1. When your code crashes, run it in a debugger. This will pinpoint the location of the crash, and will let you examine the state of the program. This is often enough to understand the root cause of the problem.

2. Use std::vector instead of raw arrays.