c++ - 在巢中放置 cout 的适当位置

Question

编辑:更改为 bool 标志，但打印的内容仍然多于应有的内容:

string line; // a string to hold the current line
while(getline(myFile,line)) {
bool old_count = false; // to help determine whether the line has been output yet
for (unsigned int i = 0; i < line.length(); i++) {
    string test = line.substr( i, targ_length );
    if ( strcmp(word.c_str(),test.c_str()) == 0  ) {
        count++;
        if ( !old_count ); {
        cout << line_num << " : " << line << endl;
        } // end if
        old_count=true;
    } // end if     
} //end for
line_num++;
} // end while

/结束编辑

我的作业是编写一个程序来搜索文本文件中的单词。我已经让它完美地工作，除了它应该打印找到该单词的每一行，如果该单词在该行中出现多次，我的程序将多次打印同一行。我需要它只打印一行。我试过将 if (count != old_count) 移动到不同的地方，但运气不好，我很困惑。我的代码如下。谢谢你的帮助!

#include <iostream>
#include <fstream>
#include <string>
#include <cstring>
using namespace std;

/* minimum required number of parameters */
#define MIN_REQUIRED 3

/* display usage */
int help() {
printf("Proper usage: findWord <word> <file>\n");
printf("where\n");
printf("    <word> is a sequence of non-whitespace characters\n");
printf("    <file> is the file in which to search for the word\n");
printf("example: findWord the test.txt\n");
return 1;
}

/*
 * Program that searches for occurrences of given word within a given file
 * @return 0 (default for a main method)
 */
int main(int argc, char *argv[]) {

if (argc < MIN_REQUIRED) {
return help();
} // end if

string word = argv[1]; // the word to be searched for
string file_name = argv[2]; // the name of the file to be read

ifstream myFile(file_name.c_str()); // read the file
if (! myFile) {
cerr << "File '" << file_name << "' could not be opened" << endl;
return -1;
} // end if

cout << "Searching for '" << word << "' in file '" << file_name << "'\n";

int targ_length = word.length(); // the legnth of the string we're searching for

int count = 0; // running count of instances of word found
int line_num = 1; // number of current line

string line; // a string to hold the current line
while(getline(myFile,line)) {
int old_count = count; // to help determine whether the line has been output yet
for (unsigned int i = 0; i < line.length(); i++) {
    string test = line.substr( i, targ_length );
    if ( strcmp(word.c_str(),test.c_str()) == 0  ) {
        count++;
    } // end if
    if ( old_count != count ); {
        cout << line_num << " : " << line << endl;
    } // end if     
} //end for
line_num++;
} // end while

cout << "# occurrences of '" << word <<" ' = " << count << endl;

return 0;
}

Answer 1

尝试将 int 标志更改为 bool 标志，如下所示:

while(getline(myFile,line)) {
bool old_count = false; // to help determine whether the line has been output yet
bool second_flag = false;
for (unsigned int i = 0; i < line.length(); i++) {
    string test = line.substr( i, targ_length );
    if ( strcmp(word.c_str(),test.c_str()) == 0  ) {
        old_count = true;
    } // end if
    if ( old_count && !second_flag ){
        cout << line_num << " : " << line << endl;
        second_flag = true;
    } // end if     
} //end for
line_num++;
} // end while