如何顯示從文件讀取的整數的最小值和最大值？

Question

以下是我的代碼。我的算法有問題。它顯示來自輸入文件的最大值和最小值的整數值。值。請有人看看並告訴我我做錯了什麼？

#include "cstdlib" 
#include "iostream" 
#include "fstream" 

using namespace std; 

int main() 
{ 
    fstream instream; 
    ofstream outstream; 
    instream.open("num.txt"); 
    if(instream.fail()) 
    { 
     cout<<"The input file failed to open\n"; 
     exit(1); 
    } 
    outstream.open("output.txt"); 
    if(outstream.fail()) 
    { 
     cout<<"The output file failed to open"; 
     exit(1); 
    } 

    int next, largest, smallest; 
    largest = 0; 
    smallest = 0; 

    while(instream>>next) 
    { 
     largest = next; 
     smallest = next; 
     if(largest<next) 
     { 
      largest = next; 
     } 
     if(smallest>next) 
     { 
      smallest = next; 
     } 
    } 

    outstream<<"The largest number is: "<<largest<<endl; 
    outstream<<"The smallest number is: "<<smallest<<endl; 
    instream.close(); 
    outstream.close(); 
    return 0; 
} 

Answer 1

問題出現在這個循環中嗎？

while(instream>>next) 

    { 

    largest = next; 

    smallest = next; 

    if(largest<next) 

    { 

    largest = next; 

    } 

    if(smallest>next) 

    { 

     smallest = next; 

    } 

    } 

如果2條語句不可達，因爲最大和最小都等於next？如果while中的2 if語句從未執行，則每次迭代時最大和最小值總是被設置爲next。

Answer 2

你無條件地在每次迭代next值分配給largest和smallest：

while(instream>>next) 
    { 
     largest = next; // <-- Why are you surprised? 
     smallest = next; // <-- :) 
     if(largest<next) 
     { 
      largest = next; 
     } 
     if(smallest>next) 
     { 
      smallest = next; 
     } 
    } 

Answer 3

程序往往會做什麼，他們被告知。這就是你要做的：

while(instream>>next) { 
     largest = next; 
     smallest = next; 

這是你總是將它們設置爲最新的地方。也許改變這些三線這樣的：

largest = 0; 
smallest = –0; 
while(instream>>next) { 

Answer 4

#include<cstdlib> 
#include<iostream> 
#include<fstream> 

using namespace std; 

int main() 
{ 
    fstream instream; 
    ofstream outstream; 
    instream.open("joy.txt"); 
    if(instream.fail()) 
    { 
     cout<<"The input file failed to open\n"; 
     exit(1); 
    } 
    outstream.open("output.txt"); 
    if(outstream.fail()) 
    { 
     cout<<"The output file failed to open"; 
     exit(1); 
    } 

    int next, largest, smallest; 
    largest = 0; 
    smallest = 0; 


    while(instream>>next) 
    { 

     if(largest<next) 
     { 
      largest = next; 
     }else{ 
        smallest = next; 
     } 
    } 

    outstream<<"The largest number is: "<<largest<<endl; 
    outstream<<"The smallest number is: "<<smallest<<endl; 
    instream.close(); 
    outstream.close(); 

    system("pause"); 
    return 0; 
}