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这个让我有点困惑......希望在阅读源文件后，你可以帮助解决我的困境。
程序：存储一组数字（手动/从文件）;扫描阵列并计算特定范围之间的数字。 （0-24,24-49,50-74等，直到200）;然后在屏幕上显示计数或保存到.txt文件。
// Program for teachers to input test grades.
// Test scores range from 0-200.
// Test scores can either be input by file, or manually.
// Program will then display the number of test scores that falls
// into quarter ranges.
// Display options are either on screen or in file.
#include "stdafx.h"
#include <iostream>
#include <fstream>
using namespace std;
// Due to being new with functions, I was not sure if these variables
// need to be constant or not...
char scores;
int students;
int i,n, list[100];
void openinfile(ifstream &infile);
void openoutfile(ofstream &outfile);
int count(int x, int y);
ifstream inputfile;
ofstream outputfile;
// Using VS2013
// Main program for options menu's and algorithms.
int main(int argc, char *argv[])
{
int total;
int qMenu1;
int qMenu2;
cout << "How many students are in your class?" << endl;
cin >> students;
cout << "How would you like to enter your test scores?" << endl;
cout << "1 - From File." << endl;
cout << "2 – Manually." << endl;
cin >> qMenu1;
if (qMenu1 = 1)
openinfile(inputfile);
else if (qMenu1 = 2)
{
cout << "Please enter total number of students." << endl;
cin >> students; // Store array size in students.
// Sets up the array for the user to enter all grades, 1 by 1
// until the the entries = max number of array slots.
for (i=0; i<students-1; i++)
{
cout << "Enter test score #" << i << ":" << endl;
cin >> list[i];
}
}
else
{
cout << "Please enter a valid Number." << endl;
cout << "(1 or 2)" << endl;
}
// Menu2: Display options. (On Screen or Save to File)
cout << "How would you like your results displayed?" << endl;
cout << "1 – On Screen." << endl;
cout << "2 – To File." << endl;
cin >> qMenu2;
if (qMenu2 = 1)
{
cout << "TOTAL NUMBER OF STUDENTS WITHIN RANGE:" << endl;
cout << endl;
total = count(0, 24); // Quarter ranges that the input
cout << "000 – 024\t" << total << endl; // needs to be checked against.
total = count(25, 49);
cout << "025 – 049\t" << total << endl;
total = count(50, 74);
cout << "050 – 074\t" << total << endl;
total = count(75, 99);
cout << "075 – 099\t" << total << endl;
total = count(100, 124);
cout << "100 – 124\t" << total << endl;
total = count(125, 149);
cout << "125 – 149\t" << total << endl;
total = count(150, 174);
cout << "150 – 174\t" << total << endl;
total = count(174, 200);
cout << "174 – 200\t" << total << endl;
}
else
{
openoutfile(outputfile);
outputfile << "TOTAL NUMBER OF STUDENTS WITHIN RANGE:" << endl;
outputfile << endl;
total = count(0, 24);
outputfile << "000 – 024\t" << total << endl;
total = count(25, 49);
outputfile << "025 – 049\t" << total << endl;
total = count(50, 74);
outputfile << "050 – 074\t" << total << endl;
total = count(75, 99);
outputfile << "075 – 099\t" << total << endl;
total = count(100, 124);
outputfile << "100 – 124\t" << total << endl;
total = count(125, 149);
outputfile << "125 – 149\t" << total << endl;
total = count(150, 174);
outputfile << "150 – 174\t" << total << endl;
total = count(174, 200);
outputfile << "174 – 200\t" << total << endl;
outputfile.close();
return 0;
}
}
// Function to open file for reading and input in array.
void openinfile(ifstream &infile)
{
char filename[100];
cout << "Enter the file name: ";
cin >> filename;
infile.open(filename);
if (infile.fail())
cout << filename << "\tDoes not exist" << endl;
else
{
cout << filename << "Successfully open" << endl;
// read character until the end of file.
for (int i = 0; i < 100; i++)
{
infile >> list[i];
}
}
}
// function to open new file for writing result to.
void openoutfile(ofstream &outfile)
{
char filename[100];
cout << "Enter the file name to save.";
cin >> filename;
outfile.open(filename);
if (outfile.fail())
{
cout << filename << " could not be saved." << endl;
}
else
{
cout << filename << "Successfully saved!" << endl;
}
}
// function to count numbers within a certain range.
int count(int x, int y) // ((x >= 0)&&(x <= 24))
{
int numOf = 0; // variable counter
int target;
target = (( target >= x)&&(target <= y));
for(int cntr = 0; cntr < students; cntr++)
{
if(list[students] == target)
{
numOf += 1; // adds 1 for every number found between
} // range target.
return numOf; // returns number of occurances found.
}
}
最后一个功能是我的问题所在，我不太确定如何解决这个问题。任何帮助都会很精彩！ -Chris -
答案 0 :(得分：2)
你对比较感到困惑：
target = (( target >= x)&&(target <= y));
target未定义，但您正在检查它是否在所需范围内，然后将其设置为布尔值。然后，您将测试数组中的任何元素是否等于该值。此外，您将在第一次迭代后返回循环内部。
让我们解决所有这些问题，我相信你会意识到这已经是深夜了，你喝的咖啡太多了，而你并没有直接思考：
int count(int x, int y)
{
int numOf = 0;
for(int cntr = 0; cntr < students; cntr++) {
if( list[ctr] >=x && list[ctr] <= y ) numOf++;
}
return numOf;
}
现在，有更好的方法可以做到这一点。例如，您可以使用整数除法计算一个循环中的所有范围。如果您确定所有值都在有效范围内，则可以这么简单：
int counts[8] = {0};
for( int i = 0; i < students; i++ ) counts[list[i]/25]++;
此外，没有理由因为您正在写入流来复制输出的代码。将代码移动到函数中：
void output( ostream & s ) {
s << "TOTAL NUMBER OF STUDENTS WITHIN RANGE:" << endl;
// etc...
}
然后：
if (qMenu2 = 1)
{
output(cout);
} else {
openoutfile(outputfile);
output(outputfile);
outputfile.close();
}
答案 1 :(得分：0)
不是修复代码本身，而是将您所看到的内容称为Bucket Sort。您需要一组计数器，而不仅仅是一个，并且您希望使用输入数字来确定要递增的计数器。
如果我正确地阅读您的介绍，那么您有一个巨大的优势。您的“桶”用于连续的数字范围，每个范围的大小相同。
所以，如果你还没有想到它，你会想要一个计数器数组，你可以使用整数除以25来找到每个桶的索引。
这也应该比直接比较更直接。