C++停留在无限循环之后改变什么与循环无关

Question

我写了这段代码，并且它运行良好，但是有一些格式错误，所以我改变了一些代码，并添加了一个else语句，我标记了一个在代码中发表评论。

#include <string> 
#include <iostream> 
#include <fstream> 
#include <ctype.h> 

using namespace std; 

int main(int argc, char* argv[]) { 

/*if (argc != 3) { 
    cout << "Error: wrong number of arguments." << endl; 
}*/ 

ifstream infile(argv[1]); 
//infile.open(argv[1]); 

string content((std::istreambuf_iterator<char>(infile)), 
    (std::istreambuf_iterator<char>())); 

string final; 
string temp; 
string distinct[5000]; 
string look; 
int distinctlen = 0; 
int distinctnum[5000] = { 0 }; 
int numdist = 0; 
int wordcount = 0; 
int i = 0; 
int j = 0; 
int k = 0; 
int quest = 0; 
int isdistinct = 0; 
int ismatch = 0; 
int qmatch = 0; 
int len = content.length(); 
bool wordprinted = false; 
//cout << "test 1" << endl; 
//cout << "length of string: " << len << endl; 
//cout << "content entered: " << content << endl; 
while (i < len) { 

    //cout << "test 2" << endl; 
    if (isalpha(content[i])) { 
     //cout << "test 3" << endl; 
     if (isupper(content[i])) { 
      //cout << "test 4" << endl; 
      temp.push_back(tolower(content[i])); 

     } 
     else { 
      //cout << "test 5" << endl; 
      temp.push_back(content[i]); 

     } 
    } 
    else { 
     //cout << temp << endl; 
     //cout << "test 6" << endl; 
     ++wordcount; 
     final = final + temp; 
     j = 0; 
     for (k = 0;k < numdist;k++) { 
      //cout << "test 7" << endl; 
      if (distinct[k] == temp) { 
       ++distinctnum[k]; 
       isdistinct = 1; 
       break; 
      } 
     } 
     if (isdistinct == 0) { 
      //cout << "test 8" << endl; 
      distinct[numdist] = temp; 
      ++numdist; 
     } 
     temp.clear(); 
     isdistinct = 0; 
    } 
    //cout << temp << endl; 
    ++i; 
} 
//cout << final << endl << endl; 
cout << "The number of words found in the file was " << wordcount + 1 << endl; 
cout << "The number of distinct words found in the file was " << numdist + 1 << endl << endl; 

ifstream infile2(argv[2]); 
string query((std::istreambuf_iterator<char>(infile2)), 
    (std::istreambuf_iterator<char>())); 
//cout << query << endl; 
query += ' '; 

int len2 = query.length(); 
int looklen; 
//cout << quest << endl; 
for (i = 0;i < len2;i++) { 
    if (query[i] == '?') { 
     quest = 1; 
    } 
    else if (isspace(query[i])) { 
     //cout << "test1" << endl; 
     if (quest == 0) { 
      //cout << "test2" << endl; 
      for (j = 0;j < numdist;j++) { 
       if (look == distinct[j]) { 
        ismatch = 1; 
        cout << look << " : matches " << look << " " << distinctnum[j]+1 << " time(s)." << endl; 
        break; 
       } 
      } 
      if (ismatch == 0) { 
       cout << look << " : no match." << endl; 
      } 
      ismatch = 0; 
     } 
     else { 
      //cout << "test" << endl; 
      looklen = look.length(); 
      //cout << looklen << " " << look << endl; 
      for (j = 0;j < numdist;j++) { 

       for (k = 0;k < looklen;k++) { 

        //cout << k << endl; 
        if (looklen < distinct[j].length()) { 
         break; 
        } 
        if (look[k] == '?' && (k + 1) == looklen && wordprinted == false) { 
         cout << look << " : matches " << distinct[j] << " " << distinctnum[j] + 1 << " time(s)." << endl; 
         k++; 
         wordprinted = true; //NEW LINE ADDED 
         cout << "wordprinted = true" << endl; 
         break; 
        } 
        else if (look[k] == '?' && (k+1) == looklen && wordprinted == true) { //NEW CODE ADDED THAT BROKE IT 
         for (i=0;i < looklen;i++) { 
          cout << " "; 
         } 
         cout << " "; 
         cout << "matches " << distinct[j] << " " << distinctnum[j] + 1 << " time(s)." << endl; 
         break; 
        } 
        else if (look[k] == distinct[j][k]) { 
         k++; 
        } 
        else if (look[k] == '?') { //check for space 
         k++; 
         continue; 
        } 

        else if (look[k] != distinct[j][k]) { 
         break; 
        } 
        if ((k + 1) == looklen) { 
         //cout << "test3" << endl; 
         cout << look << " : matches " << distinct[j] << " " << distinctnum[j] + 1 << " time(s)." << endl; 
         break; 
        } 

       } 

      } 
      wordprinted = false; 
      cout << "wordprinted = false" << endl; 
     } 
     look.clear(); 
     continue; 
    } 
    look.push_back(query[i]); 
    //cout << "test" << endl; 
    cout << len2 << endl; 

} 
return 0; 

}

从输出我得到轻微的摘录：

wordprinted =假
wordprinted =假
wordprinted = false
一个?? ：比赛和4次（S）。
wordprinted = true
相当于1次（s）。
符合1次（s）。
wordprinted =假
wordprinted =假
wordprinted =假
的ΔΣ ：比赛和4次（S）。
wordprinted = true
相当于1次（s）。
符合1次（s）。

Answer 1

您在新代码中重新使用了i索引。每次都会从外部循环中重置计数器。要小心嵌套for循环。

您可以避免的一种方法是停止在程序顶部声明计数器变量。在for循环的头文件中声明它们，总是：

for(int i=0;i<len2;i++) 

然后编译器会提醒你重用了一个计数器变量。尝试并最小化变量的范围并在例如上述的设置情况下将它们实例化。全局和重用变量用于多种目的尤其糟糕。像'我'这样的匿名计数器是可以的，但是可以用它们有意义的具体范围来声明它们。