C++：输出中出现奇怪的数字

Question

对于我的学校项目，我应该用（大约）-10 和 10 之间的随机数填充一个 20 的数组。然后，我必须根据它们是负数、0 还是正数来组织这些数字.我被告知要完成打印出原始数组和新数组的程序。

出于某种原因，有组织的数组在某些空格中打印出随机 (TYPE:long) 数字。我不确定为什么会这样。下面是我的代码：

#include <iostream>
#include <stdlib.h>
#include <time.h>

int main(int argc, const char * argv[]) {
// insert code here...
srand(time(NULL));
int numbers[20], final[20], first = 1, second = 1;

std::cout << "Enter 20 numbers, and without sorting, this program will take them and organize them based on positive, negative, and 0.\n\n";
for(int i = 0; i < 20; i++){
    std::cout << "Enter number " << (i+1) << ": ";
    //std::cin >> numbers[i];
    numbers[i] = (rand()%20 -10);
    std::cout << numbers[i] << std::endl;
}

//Numbers lower than 0
for(int i = 0; i < 20; i++){
    if(numbers[i] < 0){
        final[i] = numbers[i];
        first++;
    }
}
//Numbers equal to 0
for(int i = first; i < 20; i++){
    if(numbers[i] == 0){
        final[i] = numbers[i];
        second++;
    }
}
//Numbers greater than 0
for(int i = second; i < 20; i++){
    if(numbers[i] == 0){
        final[i] = numbers[i];
    }
}

std::cout << "This is your original array: ";
for(int i = 0; i < 20; i++){
    std::cout << numbers[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

std::cout << "This your new, organized, array: ";
for(int i = 0; i < 20; i++){
    std::cout << final[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

system("pause");
return 0;
}

我的输出是这样的：

Enter 20 numbers, and without sorting, this program will take them and organize them based on positive, negative, and 0.

Enter number 1: -6
Enter number 2: 0
Enter number 3: -4
Enter number 4: -5
Enter number 5: 0
Enter number 6: -4
Enter number 7: -5
Enter number 8: -5
Enter number 9: -8
Enter number 10: 5
Enter number 11: 0
Enter number 12: -3
Enter number 13: 5
Enter number 14: -5
Enter number 15: 7
Enter number 16: 2
Enter number 17: 9
Enter number 18: 9
Enter number 19: 3
Enter number 20: 2
This is your original array: -6, 0, -4, -5, 0, -4, -5, -5, -8, 5, 0, -3, 5, -5, 7, 2, 9, 9, 3, 2 


This your new, organized, array: -6, 1879110449, -4, -5, 0, -4, -5, -5, -8, 1, 0, -3, 1606416384, -5, 1606423158, 32767, 1606416416, 32767, 1606416416, 32767"

提前感谢所有回复的人。非常感谢。

Answer 1

final 数组的索引器应独立于 numbers 数组的索引器 (i) 增加。换句话说：

int idxFinal = 0; // determines where on the 'array' index to insert next

for(int i = first; i < 20; i++){
    if(numbers[i] < 0){
        final[idxFinal] = numbers[i];
        first++;
        idxFinal++;
    }
}

...

//Numbers equal to 0
for(int i = first; i < 20; i++){
    if(numbers[i] == 0){
        final[idxFinal++] = numbers[i];
        second++;
    }
}

您的代码的另一个问题是 //Numbers greater than 0 部分中 if 语句中的拼写错误。我会让你自己想一想 :)

Answer 2

你没有把数字放在正确的 final 数组位置，检查现在 first 是如何用来标记下一个元素应该放在最终数组中的位置的：

我还删除了未使用的 second 变量

#include <iostream>
#include <stdlib.h>
#include <time.h>

int main(int argc, const char * argv[]) {
// insert code here...
srand(time(NULL));
// changed first = 1 to first = 0 and eliminated second
int numbers[20], final[20], first = 0;

std::cout << "Enter 20 numbers, and without sorting, this program will take them and organize them based on positive, negative, and 0.\n\n";
for(int i = 0; i < 20; i++){
    std::cout << "Enter number " << (i+1) << ": ";
    //std::cin >> numbers[i];
    numbers[i] = (rand()%20 -10);
    std::cout << numbers[i] << std::endl;
}

//Numbers lower than 0
for(int i = 0; i < 20; i++){
    if(numbers[i] < 0){
        // now it is put in final[first] instead of final[i] 
        final[first] = numbers[i];
        first++;
    }
}
//Numbers equal to 0
//changed i to start from 0 again
for(int i = 0; i < 20; i++){
    if(numbers[i] == 0){
        final[first] = numbers[i];
        first++;
    }
}
//Numbers greater than 0
for(int i = 0; i < 20; i++){
    if(numbers[i] > 0){ // Yeah, here was the typo... replaced `==` with `>`
        final[first] = numbers[i];
        // added this increment
        first++;
    }
}

std::cout << "This is your original array: ";
for(int i = 0; i < 20; i++){
    std::cout << numbers[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

std::cout << "This your new, organized, array: ";
for(int i = 0; i < 20; i++){
    std::cout << final[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

system("pause");
return 0;
}

Answer 3

你在输出中得到奇怪的数字，因为你的代码没有完全填满数组（它打印出那些内存位置上已经存在的内容）。

无需给出代码（您就快完成了）：

你应该在整个数组大小（0 到 20）中迭代你的 for 循环（所有这三个），记住在这些循环中你试图检查值，所以你需要去通过所有这些。
根据您的计数器（first、second）而不是根据 i 分配给您的最终数组。同样，i 仅用于遍历数组。这会导致你的阵列在这里有洞。当您输入 if 语句时，您只是在为 final 赋值，并且仅在它们各自的位置 (i).
您对大于零的数字的 if 语句不正确，它会检查是否相等。
用 0 而不是 1 初始化 first 和 second。

应该可以了。作为旁注，您实际上并不需要两个单独的计数器，first 和 second。您可以只使用一个，在第一个循环中递增它，然后在第二个循环中继续递增它，依此类推。

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